Nanophotonic parametric quantum information processor

Abstract

A photonic integrated circuit comprising one or more waveguides including a second-order nonlinearity configured to act on optical pulses having a pulse length measured at full width at half maximum of less than 1000 optical cycles, the circuit being configured to generate, manipulate, and / or measure one or more quantum states carried in the one or more optical pulses.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. §199(e) of co-pending and commonly assigned U.S. Provisional Patent Application No. 63 / 299,762 (Reference No. CIT-8775-P), entitled “NANOPHOTONIC PARAMETRIC QUANTUM INFORMATION,” filed on January 14, 2022 by Alireza Marandi, Rajveer Nehra, Ryoto Sekine, and Luis Ledezma, which is incorporated herein by reference.

[0002] [Statement Regarding Federally Sponsored Research and Development] This invention was made with Government support under Grant Nos. ECCS1846273 and CCF1918549 awarded by the National Science Foundation, Grant No. FA9550-20-1-0040 awarded by the Air Force, Grant No. W911NF-18-1-0285 awarded by the Army, and Grant No. 80NMO0018D0004 awarded by NASA. The U.S. Government has certain rights in this invention. [Technical field]

[0003] The present invention relates to photonic integrated circuits that exploit second-order nonlinearity in waveguides to create, manipulate, and / or measure quantum states, and methods and systems that employ such photonic integrated circuits. [Background technology]

[0004] Quantum information processing holds great promise for computation, secure communication, metrology, and sensing. Many physical platforms, such as nuclear spins, superconducting circuits, photonics, trapped ions, quantum dots, and neutral atoms, have been widely investigated with the aim of building quantum information processors (1). Among them, photonics stands out for its potential in scalability, room temperature logical operations, and ease of encoding quantum information in both discrete and continuous variables. However, it remains challenging to generate, manipulate, and measure quantum states in photonic systems with the performance required for scalable quantum information systems. The present disclosure addresses this need. Summary of the Invention

[0005] Non-limiting examples of methods, devices, and systems according to embodiments described herein include the following.

[0006] [1] A photonic integrated circuit comprising one or more waveguides including second-order nonlinearity, the waveguides configured to act on classical and / or quantum optical pulses, the classical and / or quantum optical pulses having pulse lengths, measured at full width at half maximum of the classical field value or quantum wave function of each pulse, respectively, less than 1000 optical cycles, the waveguides comprising at least generation of one or more quantum states carried by one or more optical pulses; Manipulation of one or more quantum states, or Measuring one or more quantum states Photonic integrated circuits.

[0007] [2] The photonic integrated circuit of example [1], wherein the waveguide has a width and height, respectively, less than 5 μm, and / or the waveguide has phase matching and / or dispersion engineering for nonlinear interaction of optical pulses having a bandwidth in the range of 0.1 to 100 THz.

[0008] [3] the one or more waveguides comprise an optical parametric amplifier (OPA); and / or a photonic integrated circuit comprising an optical parametric oscillator (OPO) including one of said waveguides; the OPA or the OPO generates the quantum state including a signal pulse and / or an idler pulse in response to a pump pulse using a second-order parametric process; the waveguides are configured such that dimensions including the height, the width, and the length minimize a velocity mismatch (GVM) between the pump pulses and the signal pulses and / or between the pump pulses and the idler pulses, respectively, such that the pump pulses and the signal pulses and / or the pump pulses and the idler pulses overlap in time; The photonic integrated circuit of Example [1] or Example [2], wherein the pump pulse, the signal pulse and / or the idler pulse comprise electromagnetic waves that are confined and guided within respective waveguides. In one or more embodiments, these waveguide dimensions also minimize group velocity dispersion (GVC), resulting in high nonlinear efficiency.

[0009] [4] The photonic integrated circuit of any of Examples [1] to [3], wherein the quantum states include Gaussian states, each Gaussian state including a squeezed vacuum state having one or more modes.

[0010] [5] The waveguide comprises at least an optical parametric amplifier including phase matching and / or dispersion engineering for a second-order parametric amplification process involving a first pump pulse and a vacuum signal field; The photonic integrated circuit of Example [4], wherein the second order parametric amplification process amplifies the vacuum signal field in a first quadrature and attenuates the vacuum signal field in a second quadrature that is orthogonal to the first quadrature, thereby generating one or more signal pulses that convey one of the first quantum states comprising a vacuum squeezed state.

[0011] [6] The photonic integrated circuit of example [5], wherein at least one of the intensity of the first pump pulse, the phase matching, the dispersion engineering, or the length of the optical parametric amplifier is adapted for a second-order parametric amplification process involving a non-degenerate parametric amplifier, whereby the signal pulse conveying the squeezed vacuum state comprises at least two modes.

[0012] [7] The photonic integrated circuit of example [5] or example [6] further comprising a second OPA, the second OPA having at least one of a second phase matching, a second dispersion engineering, or a second length tuned for an additional second-order nonlinear interaction with a second pump pulse and a signal pulse including the first quantum state, the second pump pulse having a phase difference and intensity relative to the first pump pulse, whereby the additional second-order nonlinear interaction can include the parametric amplification in a linear (non-saturated) region that amplifies one of the quadrature phases of the first quantum state, forming a second quantum state in a macroscopic region, in which the average number of photons in the quantum state is greater than 10 and less than 10^9, thereby enabling a loss-tolerant (decoherence-tolerant) quantum measurement of the first quantum state.

[0013] [8] The photonic integrated circuit of example [1] to example [3], wherein the quantum states include non-Gaussian states, each of which includes one or more cat states, one or more binomial code states, one or more Gottesman-Kitaev-Preskill (GKP) states, or one or more photon pair states.

[0014] [9] The photonic integrated circuit of any one of examples [1] to [8], comprising a modulator driven by a drive signal that enables control of the phase or intensity of optical pulses including one or more pump pulses or one or more quantum state pulses.

[0015]

[10] The photonic integrated circuit comprises an optical parametric amplifier having a phase matching, dispersion engineering, and length adapted for second-order parametric interaction with a pump pulse having the pulse length, and a vacuum field; the second-order nonlinear interaction includes parametric amplification in a saturation region, and a pump energy of the pump pulse is suppressed by about 10% through the parametric amplification; This forms a signal pulse that conveys at least one quantum state in which the Wigner function has a negative value, as in the photonic integrated circuit of example [1] to example [3], example [8] or example [9].

[0016]

[11] The photonic integrated circuit includes one or more components for manipulating the one or more quantum states, the one or more components comprising: one or more modulators that manipulate the intensity or phase of said quantum states; A coupler that couples multiple quantum states, or one or more spectral filters, one or more spectrally dependent splitters, one or more polarization rotators, or one or more Mach-Zehnder interferometers A photonic integrated circuit comprising at least one of the following: Example [1] to Example [3], Example [4], Example [8], Example [9], or Example

[10] .

[0017]

[12] The photonic integrated circuit comprises at least Designing or detecting quantum states, or The photonic integrated circuit of example [1] to example [3], example [4], example [8], example [9] or example

[10] further comprising one or more single photon detectors, one or more photon number-resolving detectors, and / or one or more homodyne detectors configured to enable a quantum computing task using the quantum state.

[0018]

[13] one or more inputs connected to the waveguide; and one or more outputs coupled to said waveguide Further comprising: the optical pulses include one or more input pulses and one or more output pulses output from the output in response to the input pulses received at the input; the waveguide is configured at least to generate, manipulate, or measure one or more optical pulses conveying one of the different quantum states representing different bits of information according to a time division multiplexing scheme; The light pulses are distributed among different equally spaced time bins; the different equally spaced time bins may be routed to different ones of the waveguides using one or more first modulators and one or more first couplers interconnected via one or more first delay lines; The equally spaced different time bins can be combined using one or more second couplers and one or more second delay lines, thereby coupling quantum states in the different time bins, as in the photonic integrated circuits of examples [1] to

[12] .

[0019]

[14] A photonic integrated circuit according to any one of examples [1] to

[13] , wherein the pulse length is in the range of 1 to 1000 femtoseconds, whereby optical pulses are routed into different equally spaced time bins having durations greater than 1 to 1000 femtoseconds and containing different bits.

[0020]

[15] configured as a processor that performs one or more quantum computations on one or more quantum states; or configured as a quantum sensor for performing quantum sensing by measuring said one or more quantum states; or configured to perform quantum state tomography of the quantum state that is robust to detection loss; or configured to perform all-optical continuously variable quantum error correction using binomial and squeezed cat codes using said quantum states; or configured to perform quantum teleportation using the quantum state; or configured to perform boson sampling in the time / frequency domain using the quantum state; or Photonic integrated circuits, such as those described in examples [1] to

[14] , configured to preserve the quantum coherence of quantum states.

[0021]

[16] The waveguide comprises an optical parametric amplifier having phase matching and dispersion engineering such that the parametric gain is in a nonlinear saturation region, thereby providing at least an all-optical linear or nonlinear quantum measurement of said quantum state; or Gaussian or non-Gaussian Photonic integrated circuits, e.g. [1] to

[15] , enable

[0022]

[17] The photonic integrated circuit of any one of Examples [1] to

[15] , further comprising a wavelength converter that converts the wavelength of the optical pulse conveying the quantum state into a different frequency range.

[0023]

[18] inputting one or more input optical pulses into one or more waveguides; generating, manipulating, or measuring one or more quantum states using one or more waveguides including a second-order nonlinearity configured to operate on optical pulses including the input pulse, each having a width and height less than 2 μm and / or a bandwidth in the range of 0.1 to 100 terahertz, and A method for processing one or more quantum states, comprising:

[0024]

[19] The generating, manipulating, or measuring is performed using a time division multiplexing scheme, the method comprising: distributing said light pulses among equally spaced time bins; routing the time bins to different ones of the waveguides using one or more modulators and one or more first couplers, each coupled to one another via one or more first delay lines; combining the different time bins using one or more second couplers and one or more second delay lines such that the quantum states of the different time bins are combined; The method of Example

[18] , wherein the waveguide comprises one or more optical parametric amplifiers and / or the waveguide is disposed in one or more optical parametric oscillators.

[0025]

[20] The generating, manipulating, and / or measuring may further comprise: performing one or more quantum computations on the one or more quantum states; performing quantum sensing by measuring said one or more quantum states; or performing quantum state tomography of said quantum state that is robust to detection loss; and performing all-optical continuously variable quantum error correction with binomial and squeezed cat codes using said quantum state. performing quantum teleportation using said quantum state; Perform boson sampling in the time / frequency domain with quantum states, or The method of example

[18] or example

[19] , comprising at least one of preserving quantum coherence of the quantum state. [Brief description of the drawings]

[0026] Reference is now made to the drawings, in which common reference numbers represent corresponding parts throughout. JPEG2025501863000073.jpg221153JPEG2025501863000074.jpg213153JPEG2025501863000075.jpg217153JPEG2025501863000076.jpg19153 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] In the following description of the preferred embodiment, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments which may be practiced in the present invention, It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.

[0028] [Technical description] In an exemplary embodiment of the invention, a photonic integrated circuit comprises a waveguide with a second-order nonlinearity configured to operate on optical pulses each having a pulse length, measured at full width at half maximum, of less than 1000 optical cycles. generating one or more quantum states carried by one or more optical pulses; Manipulate one or more quantum states; and / or Measure the quantum state, It is configured as follows.

[0029] These capabilities (creation, manipulation, and / or measurement of quantum states) are achieved through a combination of subwavelength confinement of optical modes, strong waveguide nonlinearities, high-fidelity quasi-phase matching (e.g., by periodic poling), and dispersion engineering to extend the interaction length. Current waveguide material platforms include, but are not limited to, lithium niobate (23, 24-26).

[0030] All these functions can be implemented on the same chip or on different chips.

[0031] [Quantum state] Examples of quantum states that can be generated, manipulated, and / or measured using photonic integrated circuits include, but are not limited to, Gaussian states (e.g., squeezed vacuum states, and multimode squeezed states, including cluster states) and non-Gaussian states (e.g., cat states). Waveguides with short-pulse optical parametric amplifiers can be used to generate and measure Gaussian states, and highly nonlinear low-loss optical parametric amplifiers operating near or below threshold can be used to achieve non-Gaussian states. OPAs operating in the highly nonlinear low-loss regime can be used to generate non-Gaussian states with negative values ​​of Wigner negativity, which are necessary for exponential speedup and fault tolerance.

[0032] [State manipulation and protection] Photonic integrated circuits can be configured for a variety of linear optical manipulations using beam splitters, couplers, polarization controllers, polarization rotators, or spectral filters, etc. A number of tuning mechanisms (e.g., electro-optic or thermo-optic modulators) can be employed for fine tuning of the waveguide response and / or manipulation of the state in the external driving signal. Wavelength conversion on the same chip can also be used to transfer quantum states across different spectral ranges.

[0033] Photonic integrated circuits can be configured for non-Gaussian operations by configuring networks of optical parametric oscillators and / or optical parametric amplifiers in the highly nonlinear, low-loss regime, which can respond to input quantum states in a nonlinear manner. For example, a first-order phase transition can be effectively used as the non-Gaussian operation of a quantum state.

[0034] A waveguide with a high-gain OPA operating in the linear region can be used to deterministically preserve the quantum coherence of non-Gaussian states.

[0035] [Status Measurement] Optical parametric amplifiers can be used to transfer Gaussian states from macroscopic to microscopic levels. Non-Gaussian measurements can be achieved using high-gain OPAs operated in the linear regime as single-photon or photon-number-resolved (PNR) detectors. The PNR capability can be further enhanced by spatially or temporally multiplexing high-gain OPAs within the same nanophotonic chip. Furthermore, operating the OPA in the highly nonlinear saturation regime enables not only single-photon detection but also photon-number-resolved measurements.

[0036] High-gain OPAs enable quantum state characterization (e.g., quantum state tomography) that is robust to detection losses.

[0037] [Application Architecture] In continuously variable (CV) quantum photonics, information is encoded into continuous amplitude and phase values ​​in a quantized electromagnetic field. Single-mode and multimode squeezed states can be widely used in a variety of applications, including quantum-enhanced interferometry (3), microscopy (4), and quantum teleportation. Furthermore, highly entangled CV quantum states, i.e., cluster states (6-8), serve as universal sources for one-way quantum computation. In general, such high-quality CV states are generated from single-mode or two-mode squeezed vacuums, which are induced using second-order parametric processes in bulk crystals or large-area waveguides. These CV quantum states can be realized using the photonic integrated quantum circuits described herein.

[0038] In one embodiment, the photonic integrated circuit is configured for all-optical continuously variable quantum error correction with binomial code and squeezed cat code.

[0039] In another embodiment, the photonic integrated circuit is configured for all-optical quantum teleportation (eg, quantum communication networks).

[0040] In yet another embodiment, a photonic integrated circuit is configured for on-chip boson sampling in the time / frequency domain using high-gain OPAs for state generation and photon-counting measurements.

[0041] [First example: Photonic integrated circuits for generating, manipulating, and measuring squeezed vacuum states (see also Ref. 51)] A. System The first OPA generates a microscopic squeezed vacuum, which is then amplified to a macroscopic level by a high-gain OPA in the same nanophotonic chip. The resulting macroscopic field carries information about the microscopic squeezed state and can be measured with high tolerance to losses.

[0042] Figure 1A shows the phase-space distributions of the vacuum (black circles) and the phase-quadrature squeezed vacuum (filled ovals). The measurement (second) OPA selects a particular quadrature of the microscopic squeezed field and amplifies it to a macroscopic level, in principle without adding noise. In Figures 1B and 1C, the phase-space distributions (filled ovals) corresponding to the amplified antisqueezed quadrature and the amplified squeezed quadrature are plotted against the pump phase Φ of the two particular measurement OPAs. pump2 Φ pump1 = 0 and use this as the reference for the phase of Pump 2.

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[0045] In the ideal case, squeezing (anti-squeezing) is

number

[0046] For the data presented here, the squeezer (low gain) and measurement (high gain) OPAs of the circuit are periodically poled with lengths of 2.5 nm and 5.0 nm, respectively. The output of the squeezer OPA (microscopic squeezed vacuum) is coupled to the measurement OPA via a directional coupler. An adiabatic design was used to make the directional coupler broadband and less susceptible to fabrication defects. In the adiabatic design, both waveguides are tapered, but the gap remains constant over the length of the coupler. The coupler is a waveguide towards the measurement OPA that directs the squeezed vacuum to the original and adjacent waveguides, and keeps the residual pump of the squeezer OPA in the original waveguide (Figure 1D).

[0047] The fabricated adiabatic coupler induces about 30% loss in squeezed vacuum and about 20% leakage of squeezer pump in measured OPA. Numerical simulations show that by properly calibrating the fabrication steps, the coupling performance of the adiabatic coupler can be improved by about 98% for squeezed signal and about 5% for squeezer pump, which improves the measurement quality.

[0048] Figure 2A shows the experimental setup used to acquire the data in Figures 2B-2E and 3A-3D. The system is equipped with a squeezer OPA and a measurement OPA pumped by a mode-locked laser (Menlo Systems Orange A), which generates practically transform-limited pulses of 75 fs length at a repetition rate of 250 MHz. The relative phase between the pulses of pump 1 (squeezer OPA) and pump 2 (measurement OPA) was modulated by a piezoelectric transducer (PZT) on the pump 2 arm. At the output of the nanophotonic chip, the amplified squeezed signal and the measurement OPA pump were first separated using a die lock mirror and then detected by two different optical spectrum analyzers (OSA). Figure 2A shows (i) a pseudocolor scanning electron microscope (SEM) image of the nanophotonic circuit, (ii) a magnified SEM image of the coupler region, and (iii) a pseudocolor second harmonic microscope image of the periodically poled region before etching the waveguide.

[0049] b. Characterization results (i) Measurement of squeezed light Figure 2B shows an example of a measurement of the generated squeezed state. The green trace shows the measured OPA output signal using the OSA in zero-span mode at 2090 nm while keeping both pump 1 and pump 2 on and modulating the PZT with a 1-Hz ramp signal. To accurately measure squeezing, the effect of the residual interference of the two pumps in the measured output was removed. This was achieved by determining the maximum and minimum of the residual interference and then calibrating the amplified shot noise level by varying the power of pump 2 to these maximum and minimum pump powers while blocking pump 1. These two levels of pump 2 are the "shot noise maximum" and "shot noise minimum" shown in Figure 2B. Meanwhile, the "intrinsic shot noise" corresponds to the level of pump 2 during the squeezing measurement. Thus, in the squeezing measurement, the shaded area below (above) the shot noise minimum (shot noise maximum) corresponds to the squeezing (anti-squeezing) at the input of the high-gain OPA. With the squeezer OPA pump energy set to 0.8 pJ, the squeezing level was measured to be 4.2 ± 0.2 dB and the anti-squeezing level was measured to be 9.7 ± 0.1 dB, respectively. For details of the shot noise calibration measurement, see the description of the shot noise measurement below.

[0050] Figure 2C shows the dependence of squeezing on pump power at 2090 nm, measured while keeping pump 2 constant and performing shot noise calibration for each power level. As the pump power of the squeezer OPA increases, the measured squeezing level initially increases. However, as the pump pulse energy exceeds 0.8 pJ and the squeezer pump is further increased, the measured squeezing level decreases. The degradation of the measured squeezing at high pump powers can be attributed to the small phase noise and chirp existing between pump 1 and pump 2, which may cause a mixture of loss-degraded squeezed quadrature and relatively large antisqueezed quadrature (27). In addition, parasitic nonlinear effects, such as photorefractive effects and nonlinear absorption mechanisms in the waveguide, may also cause the degradation of squeezing at high pump powers.

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[0053] (ii) Broadband measurements Figures 3A-3C show the results of broadband squeezing measurements. The amplified shot noise is calibrated across the spectrum in the same way as described above. The green traces correspond to measurements with the OSA in three different spectral windows when the PZT is modulated with a 300 mHz slow ramp signal. Squeezing is present across the spectrum with a slight spectral dependence. The measured squeezing is 3.8 ± 0.4 dB around 1950 nm, 4.2 ± 0.2 dB around 2090 nm, and 4.9 ± 0.2 dB around 2200 nm. The spectral dependence is due to the wavelength-dependent coupling efficiency of the adiabatic coupler. The squeezing bandwidth is measured to be 25.1 THz and is expected to increase up to 36.4 THz. This can be confirmed by the optical parametric generation (OPG) from the squeezer OPA in Figure 3D. The measured squeezing bandwidth is largely limited by a small mismatch in the measured OPA gain in the spectral wings, as evident from the OPG signal. Due to this difference in gain spectrum, the measured OPA does not amplify the squeezed vacuum to macroscopic levels over the entire generation bandwidth, resulting in a reduced measured squeezing bandwidth. These measurements show that the generated squeezed states can occupy a record-level time window of about four optical cycles. This time window can be further shortened by devising dispersion engineering and quasi-phase matching (29), which may lead to opportunities for studying quantum fields in the ultrashort pulse regime (30). The demonstrated squeezing bandwidth allows the definition of temporal bins of several optical cycles in time-multiplexed CV quantum information processors (6, 7). As a result, such ultrashort time bins can be defined with a high density, allowing the use of centimeter-scale on-chip delay lines to cluster states on a large scale.

[0054] [Further examples characterizing the first example (see also reference 51)] 1. Experimental Setup Details The experimental setup for the generation of the squeezed states and the all-optical measurements is shown in Figure 2F. The squeezer OPA and the measurement OPA are pumped by a mode-locked Yb fiber laser (Menlo Systems Orange A), which produces ~75 fs long pulses at a repetition rate of 250 MHz centered at ~1045 nm. The pump laser is first split into two paths, pump 1 and pump 2 in Figure 2. The first beam (labeled pump 2) is sent to a delay stage equipped with a micrometer arm used for fine adjustment of the temporal overlap, while the coarse adjustment is achieved by adjusting the position of the delay stage. Depending on the measurement at hand, the second output beam of the nanophotonic chip, the amplified squeezed signal and the measurement OPA pump, are separated using a dichroic mirror and detected by an optical spectrum analyzer (OSA) for spectral measurements. PBS: polarizing beam splitter, HWP: half-wave plate, DM: dichroic mirror, Obj: reflective objective, VND: variable neutral density filter, FC: fiber coupler, OSA: optical spectrum analyzer, PD: photodetector, OPO: optical parametric oscillator, FM: flip mirror. Pump 1 is guided to a synchronously pumped degenerate optical parametric oscillator (SPDOPO) used to generate pulses at 2090 nm in the chip setup or (32). For the squeezing measurement, pump 1 and pump 2 are first combined with a 50:50 beam splitter (BS) and focused into the waveguides of both the squeezer OPA and the measurement OPA, respectively, using a single high NA reflective objective (Newport: 20102-02). At the output of the nanophotonic chip, another reflective objective (Newport: 50102-02) is used to collect the light. The pump power is controlled using two variable neutral density filters mounted on both arms. The relative phase between pump 1 and pump 2 is modulated by a piezoelectric transducer (PZT) mounted on a delay stage.At the output of the chip, the amplified squeezed vacuum and the measured OPA pump are first separated using a dichroic mirror (DM) with high transmission around 1045 nm and high reflection around 2090 nm, and then sent to two different optical spectrum analyzers (Yokogawa AQ6370D and Yokogawa AQ6375B) for spectral measurements with a resolution of 2 nm. The SPDOPO output centered at 2090 nm (32) is used for linear characterization of the device and classical gain measurement of the OPA. Pump 1 is used to pump the SPDOPO and is locked using the “Dither Lock” technique implemented by a Red Pitaya FPGA board. To control the power at 2090 nm, a variable ND filter was added to the output of the OPO. For the OPA measurement, the well-attenuated OPDOPO signal is spatially overlapped with pump 2 at the dichroic mirror installed in place of the 50:50 BS. Discussions on device characterization and OPA gain measurement are described below in Sections 4 and 7.

[0055] 2. Shot Noise Characterization Measurements Due to imperfections in the adiabatic coupler design and its fabrication, up to 20% of the squeezer OPA couples into the high-gain measurement OPA waveguide and interferes with pump 2, resulting in gain modulation in the measurement OPA. To accurately determine the amount of squeezing, the gain modulation is measured by characterizing the interference of these two pumps in the measurement OPA and removing its effect from the squeezing measurement. Figure 4A shows an example of interference fringes (green traces) of pump 1 and pump 2 acquired by an OSA in zero-span mode at 1100 nm. While keeping squeezer OPA pump 1 blocked, the power of measurement OPA pump 2 is increased (decreased) to the maximum (minimum) level of the interference fringes, which corresponds to the blue (red) trace in Figure 4A. These two power levels of pump 2 are the "shot noise maximum" and "shot noise minimum" shown in Figure 2B. To ensure that the calibration is not affected by nonlinear effects of the measurement OPA, the pump interference is measured in zero span mode at 1100 nm (red arrow in the pump spectrum in Figure 4C) to calibrate the shot noise. This is confirmed by the linear transmission measurement at 1100 nm shown in Figure 5B for measurement OPA pump 2 power levels that vary within the range of the power levels of the recorded interference fringes.

[0056] To further verify the shot noise calibration, the interference pattern shown in Figure 4A was reproduced off-chip and injected into the interference pattern measurement OPA arm while the squeezer OPA pump 1 was blocked. Figure 4D shows the transmission measured in zero-span mode at 1100 nm. The interference fringes (green trace) are shown along with the maximum (blue) and minimum (red) power levels of pump 2. Figure 4E shows the OSA output for these traces when set in zero-span mode at 2090 nm. It can be seen that the maximum and minimum power levels of the green trace in Figure 4E are within the maximum and minimum of the amplified shot noise levels. This is in stark contrast to the squeezing measurements (Figures 2A and 3), where the green trace is below / above the shot noise maximum / minimum, due to the amplification of the squeezed and antisqueezed quadrature of the original squeezed state generated by the squeezer OP.

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[0059] Figure 5 shows a weak coherent pulse (|α| 2 We present simulation results of the squeezed OPA gain when seeded with a 100 Hz pulse width (<<1) and varying the relative phase between the pump signal and the weak signal. For pump pulse energies below 1 pJ, the simulated OPA gain is below 10 dB, in good agreement with the measured gain (antisqueezing) at the same pump energy levels.

[0060] The shortest signal pulse that can be amplified in a phase-sensitive manner by the squeezer OPA is found by varying the pulse width of a weak coherent pulse from 15 fs to 100 fs while keeping the average pulse energy constant for a given pump pulse (~75 fs) and monitoring the squeezer OPA in the time domain. Figure 6B shows the ratio of the FWHM widths of the output and input pulses, R=τ out / τ in Numerical simulations show that as we continue to decrease the input pulse width from 100 fs, the amplified output pulse width remains short for input pulse widths up to 30 fs, which corresponds to 4 optical cycles or less. Beyond that point, the output pulse width starts to broaden in the time domain, as is evident from R>1 in Fig. 6B. This can be attributed to stronger detrimental effects caused by small group velocity dispersion (GVD) and group velocity mismatch (GVM) in short pulse devices. These effects can be minimized by better managing GVD and GVM through dispersion engineering. As a result, we found that the shortest pulse that the squeezer OPA can amplify while maintaining the pulse shape and obtaining high gain is 30 fs or less. The temporal and spectral evaluation of a weak coherence pulse of 30 fs or less seeded into the OPA is shown in Fig. 6C and Fig. 6D, respectively. The input pulse is shown in the blue trace, and the orange trace corresponds to the output pulse. The yellow and blue dashed lines in Fig. 6C show the FWHM (|E| 2= 1 / 2). It can be seen that the amplified pulse maintains its shape and contains less than four cycles. Figure 6D shows constant gain over the entire bandwidth at a pump energy of 4 pJ. The simulated constant gain bandwidth matches well with the measured bandwidth of optical parametric generation (OPG) from a squeezer OPA. The OPG signal is generated by amplifying (antisqueezing) the orthogonal quadrature of the vacuum field while attenuating (squeezing) the other. Thus, the generated squeezed vacuum bandwidth supports only a few optical cycles. Ideally, to measure squeezing over the entire bandwidth, one needs to ensure that the measurement OPA has the same gain bandwidth but has enough gain to amplify the microscopic squeezed vacuum to macroscopic levels, which can be achieved with LN nanophotonics.

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[0062] For a coupling region of L=400 μm, the measured bottom gap of the coupler region was below 400 nm. The measured coupling efficiency near 2 μm is below 70%, but as suggested by the simulation, the coupling efficiency can be significantly improved to below 100%. Figure 8 shows the numerical simulation of the coupling efficiency of the 2090 nm signal and the 1045 nm pump. In these simulations, a thin film thickness of 700 nm and an etch depth of 350 nm were used. The top widths are W1=1750 nm and W2=1850 nm, and the waveguide ridge angle is about 60 degrees. The three traces correspond to three different values ​​of the bottom gap at 350 nm, 400 nm, and 450 nm, respectively. When the coupler length is 300 μm, the coupling efficiency of the signal is above about 98%, but when the coupler gap is 450 nm, the coupling efficiency of the pump is less than 5%. Considering the ultra-low loss propagation in LN nanophotonics, by improving the linear coupling of the couplers, we can measure the squeezing level suitable for fault-tolerant quantum information processors.

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[0073] The first term in Eq. S44 is the reduction in squeezing due to loss of the squeezed vacuum, and the second term is the contribution of vacuum noise. The measured squeezing deteriorates as the loss L=1-η increases. However, the measured squeezing remains non-zero for η>0, and having a high initial squeezing is always advantageous, regardless of the amount of loss. Figure 10A plots the gain of the measurement amplifier required to measure the generated initial squeezing without loss. As can be seen from Figures 10A and 10B, we find that the larger the initial squeezing, the higher the gain required, and once the gain is sufficient (e.g., above 33 dB for ~11 dB squeezing), further increases in gain have no significant effect on the measurement. Sufficient gain ensures that the measured power is completely dominated by the selected amplified quadrature, and the attenuated quadrature can be considered negligible. Note that varying the gain of the measurement OPA does not change the level of measured antisqueezing as dramatically as the squeezing. Since the antisqueezed quadrature of the microscopic squeezed field has already been amplified by the squeezer OPA, it requires less gain to dominate the measured power compared to the original squeezed quadrature.

[0074] Figure 10B shows the lossy case, where the total loss of the microscopic squeezed signal is L = 1 - η = 0.30. As expected, the measurable squeezing is degraded compared to the antisqueezing in the presence of losses. Figure 10C shows the experimentally measured squeezing and antisqueezing (solid circles) at 2090 nm by varying the squeezer pump energy. In Figure 10B, the measurements in this study agree well with the expected squeezing and antisqueezing levels. Finally, in Figure 11 we show the measured gain (red dots) of the measured OPA as we increase the energy of the pump pulse. The black curve corresponds to the expected exponential fit, which agrees well with the measured gain.

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[0077] Now consider the limiting case of the gain of the measurement OPA. When the measurement OPA has no gain, i.e., G=1, the effective efficiency is η eff = η OPA η l At this time, the measured OPA transmits η OPA Then, for G>>1 and η OPA > l , the effective detection efficiency of the quadrature measurement is the overall efficiency of the OPA, i.e., η eff →η OPA Figure 13 shows that the overall detection efficiency after amplification approaches η l = 0.2, given by {0,1,1,5,3} dB(η OPA We consider the all-optical effective quantum efficiency for many NF values ​​in the range of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, l We chose η = 0.2. The effective detection efficiency of the all-optical measurement is η OPAFigure 11 shows the gain levels measured from the high-gain OPA in this study.

[0078] As a result, we find that the overall quantum efficiency of an all-optical measurement using a high-gain phase-sensitive OPA is ultimately determined by the NF of the OPA. Although the measurement can be made tolerant to losses after high-gain amplification, the quantum efficiency is limited by the NF of the OPA, so it is desirable to have NF → 0, which is especially useful for measuring highly squeezed states that are extremely sensitive to photon loss. Figure 14 shows the photon loss (L = 1-η effective ) is increased. We can see that with 10% photon loss, the 30 dB initial squeezing (blue) degrades by less than 20 dB, while the 10 dB squeezing (red) degrades by less than 3 dB.

[0079] 6. Device Fabrication The devices were fabricated using NANOLN wafers with 700 nm thick X-cut magnesium oxide doped LN (lithium niobate) on 2 μm thick silicon oxide. The fabrication process starts with periodic poling of the chip. Poling electrodes (15 mm Cr / 55 nm Au) were patterned using electron beam lithography, electron beam evaporation and metal lift-off. A pulse of ~300 V was then applied between the electrodes, inducing periodic domain inversion over an area of ​​2.5 nm for the squeezer OPA and 5.0 nm for the measurement OPA, respectively. Considering imperfections in the fabrication, the poling period was varied from 5.17 μm to 5.32 μm in 5 nm steps. The quality of poling was inspected using second harmonic microscopy, as shown in Figure 2A(iii). The devices were then patterned using electron beam lithography, using hydrogen silsesquioxane (HSQ) as an electron beam resist and 15 nm of Ti as an adhesion layer (24, 44). The pattern was transferred to the LN layer by dry etching using an inductively coupled plasma reactive ion etcher (ICP-RIE). The remaining resist and sidewall redeposition were removed by buffered oxide etchant (BOE) and RCA cleaning. Finally, the waveguide facets were mechanically polished to improve the coupling efficiency. The quality of the fabrication was inspected using SEM, and an example is shown in Figure 2A (i and ii).

[0080] 7. Amplifier Gain Measurement The parametric gain of the measurement OPA with an auxiliary weak coherent signal generated by a 2 μm SPDOPO can be measured and optimized. Phase matching can be optimized to ensure maximum amplification / de-amplification where the weak coherent pulse occurs. To fine-tune the optimal phase matching, the chip temperature is adjusted using a thermoelectric cooling (TEC) plate placed under the chip and the chip is coated with a thin layer of organic material.

[0081] Figure 2F shows the experimental setup for OPA measurements, where pump 1 is for pumping a SPDOPO whose output signal is guided into the nanophotonic chip setup. After sufficient attenuation of the OPO signal, it is coupled into the measurement amplifier together with pump 2. Figure 15 shows the measurement results. The blue trace shows the input weak coherent signal (below 1 fJ), and the grey trace corresponds to the amplified signal with pulse energy below 6 pJ in pump 2 while scanning the PZT with a 5 Hz ramp signal. The ripple is due to the phase sensitivity of the amplification process. For better visibility, a median filter was applied to the amplified signal trace and shown in red. The measured gain is more than 28 dB around 2090 nm, which is comparable to the results in (24).

[0082] 8. Squeezing in Nanophotonics Figure 16 compares the measured squeezing and bandwidth with state-of-the-art experimental demonstrations in nanophotonic platforms including silicon nitride and silica. These experimental demonstrations show relatively weak nonlinearity Χ (3) "The squeezed light is typically detected using off-chip BHDs, which are limited in the squeezing that can be measured and the available squeezing bandwidth (due to off-chip coupling losses). The squeezing measured in this work significantly exceeds these other works, both in magnitude and bandwidth."

[0083] Table S1 lists references for the nanophotonic squeezing demonstrations shown in Figure 16. [Table 1] Table S1: Demonstration of nanophotonic squeezing.

[0084] 9. Ultrafast quantum information processor using second-order nonlinear nanophotonics With regard to CV ultrafast quantum information processing, we would like to highlight the importance of our ultrashort-pulse squeezed-state source and its all-optical measurement scheme. Single-mode and two-mode squeezed vacuum states can be used as key building blocks to generate highly entangled large-scale cluster states, which serve as quantum computing “substrates” for metrology-based quantum computing (MBQC), using both time-multiplexed and frequency-multiplexed architectures (6-8).

[0085] In time-multiplexing schemes, squeezed states generated continuously from continuous-wave (CW) pumped optical parametric oscillators (OPOs) are split into independent time bins, which are then entangled with each other using optical delays and linear optics to generate large cluster states (6, 7). In such calibrations, the repetition rate of the time bins is limited by the bandwidth of the squeezer OPOs, which are typically less than 100 MHz, resulting in temporal bins on the scale of tens of nanoseconds (lengths of tens of meters or less). As a result, to entangle thousands of temporal bins, kilometer-scale optical delays are required, which have so far been implemented using optical fibers in tabletop experiments (6, 7), making them unsuitable for on-chip integration. For these reasons, it is advantageous to shorten the length of these time bins, and thus the optical delays, which can be achieved by using ultrashort-pulse squeezed states (spanning bandwidths of THz or more). This allows the definition of femtosecond-scale temporal bins, allowing entanglement of thousands of time bins and tens of centimeter-scale optical delays, which are suitable for on-chip integration.

[0086] The squeezing bandwidth of over 25 THz and the confinement time of several optical periods demonstrated in this work are an important step toward realizing such large-scale cluster states in the rapidly advancing LN nanophotonics. In MBQC with CV cluster states, quantum computation is usually performed by homodyne measurements and gated teleportation, and homodyne measurements are also required for feedforward operations. As a result, the electronic bandwidth of the homodyne detector limits the clock rate of quantum computation. Our high-gain OPA can be used to perform all-optical loss-tolerant measurements and gated teleportation (50), which enables ultrafast MBQC with CV cluster states.

[0087] 9.1 Generation of cluster states and all-optical measurements The quantum circuit for generating one-dimensional cluster states is shown in Fig. 17. The squeezed states generated by the squeezer OPA are time-multiplexed using linear optics and on-chip optical delays. A high-gain OPA is then used to perform all-optical loss-tolerant orthogonal measurements for computation and verification of the entanglement structure.

[0088] 9.2 Non-Gaussian quantum state engineering Figure 18 shows a nanophotonic circuit for generating various non-Gaussian states (e.g., binomial code, truncated cat code, GKP code, etc.) using OPA and OPA-assisted PNR measurements. A two-mode squeezed vacuum (TMSV) state is generated by combining two orthogonal single-mode squeezed vacuum (SMSV) states at the first balanced beam splitter (BS1). The TMSV state is then sent to an interferometer for measurement by the high-gain OPA and PNA. By post-selecting a particular PNR measurement result, the aforementioned non-Gaussian states can be generated probabilistically.

[0089] 9.3 On-chip quantum-enhanced partitioning sensor Figure 19 shows a nanophotonic circuit using a squeezer OPA and a linear optical circuit to disperse the quantum entanglement into four modes to interact with the sample under characterization. After sample interaction, all the modes are coupled in the linear optical circuit and measured with a high-gain measuring OPA.

[0090] 10. Single-photon detection using nanophotonic parametric amplifiers The OPA in the high gain region can be used as a room temperature "click" detector of quantum fields at the single photon level. As shown in Figure 20, a weak quantum field described by the density matrix ρ is amplified by the OPA (pump not shown). After amplification, the macroscopic average photon number JPEG2025501863000098.jpg1483 can be measured with a normal photodiode. Figures 20B and 20C show the photon number distributions of the amplified vacuum state and single photons when the OPA gain is 20 dB. With high gain amplification, the photon number distributions of the vacuum state and the single photon state can be seen to overlap, which increases the ambiguity of distinguishing between the two. However, this ambiguity can be resolved by thresholding the classical photodetector at a certain photon number. For example, in Figures 20B and 20C, the threshold is set at a photon number of 120. This means that in the input vacuum state, the probability that there are more than 120 photons (red double-sided arrow in Figure 20B) in the amplified vacuum is essentially the dark count probability, which is P d = 0.02. Similarly, the single-photon detection efficiency is determined by the total probability that there are more than 120 photons in the amplified single-photon Fock state (red double-sided arrow in Figure 20C). As a result, in this method, the quantum efficiency η ∼ 0.20 and the dark count probability P d =0.02, single photons can be detected. The experimental setup is shown in Figure 21A. The OPA is a 5 mm long periodically poled thin-film LN waveguide, mounted on a thermal controller for fine tuning the phase matching. A Menlo Systems orange mode-locked laser was used to pump the OPA and a tabletop optical parametric oscillator (OPO) to provide a coherent signal at 2 μm. The OPO signal was attenuated to a single-photon level field. To determine the amplitude of the signal field inside the chip, the output signal was measured with the pump turned off using an ID Quantique superconducting nanowire single-photon detector optimized for 2 μm photons. The average power of the pump off-chip was 145 mW for all measurements, and a gain of over 60 dB was measured. Since the coherent state is phase sensitive, the amplified quadrature varies with the relative phase of the pump and signal fields. The phase was modulated with a piezoelectrically driven delay stage in the signal path and locked using an active feedback system (see Chapter 1 for details). The amplitude of the signal field was adjusted using a variable attenuator. The pump was removed using a long pass filter and the output signal was measured by coupling into a single mode fiber connected to an extended InGaAs photodetector with a bandwidth of 18 GHz.

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[0094] Figures 23B and 23C consider a "click" detector with quantum efficiency η = 0.10, where the cat state is reconstructed using our proposed scheme. When the OPA gain is G = 0, the reconstructed Wigner function does not retain features such as phase-space coherence and negativity. The fidelity of the reconstruction is F = 0.016. When the OPA gain is 5 dB, the fidelity is close to 1 and the Wigner function retains all its features. As a result, the proposed scheme: L=1-η=0.90 It is also tolerant to high losses.

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[0096] [Process Steps] a. Methods and devices for fabrication FIG. 26 is a flow chart illustrating a method for fabricating a photonic integrated circuit, which includes the following steps.

[0097] Block 2600 may be configured to operate with classical and / or quantum optical pulses having pulse lengths shorter than 1000 optical cycles measured in terms of the classical field value or the full width at half maximum of the quantum wave function, respectively, in order to provide a second-order nonlinearity (e.g., Χ (2) ) is designed to form one or more quantum states conveyed by one or more quantum states, manipulate one or more quantum states, or measure one or more quantum states.

[0098] In one or more embodiments, the waveguides each have a width and height of less than 5 micrometers. In one or more embodiments, the design and fabrication included phase matching and / or dispersion engineering of the waveguides for nonlinear interaction of optical pulses having a bandwidth in the range of 0.1 to 100 terahertz.

[0099] In typical examples, the waveguide comprises a waveguide that converts an input pump pulse into a signal pulse and / or an idler pulse according to a parametric interaction / amplification process with second-order nonlinearity. In these examples, dispersion engineering comprises selecting waveguide dimensions, such as length, to minimize group velocity mismatch (GVM) of the pump and signal pulses, thereby resulting in temporal overlap of the pump and signal pulses. In one or more examples, the waveguide has a length in the range of 10 microns to 1 mm, such that the difference in GVM is less than 1%.

[0100] Examples of materials having second-order nonlinearity include, but are not limited to, lithium niobate, lithium tantalate, potassium titanyl phosphate (KTP), aluminum nitride, gallium arsenide, indium phosphide, aluminum gallium arsenide, GaP, InGaP, and the like.

[0101] In one or more embodiments, the (e.g., nonlinear) material is patterned onto a substrate to form a waveguide that is comprised in a photonic integrated circuit. In one or more embodiments, the substrate is comprised of lithium niobate on silicon dioxide, and the waveguide is patterned in the lithium niobate (e.g., monolithic integration of the waveguide).

[0102] Block 2602 represents the optional coupling to the photonic integrated circuit of one or more electromagnetic radiation sources (e.g., lasers, optical parametric generators, amplifiers or oscillators, or laser systems) that output / provide optical pulses that constitute the input optical pulses.

[0103] Block 2604 represents optionally coupling the circuitry to an application (e.g., as a processor or sensor), such as a quantum computing or sensing application, or configuring the application with the circuitry.

[0104] Block 2606 represents the end result, a photonic integrated circuit, or a system or chip comprised of photonic integrated circuits. Examples include, but are not limited to:

[0105] (1) Figures 1, 17, 18, 19, 23, and 24 show photonic integrated circuits 100, 1700, 1800, 1900, 2300, 2400, which comprise: One or more of the waveguides 102, 1801, 1702 may have a second-order nonlinearity (e.g., Χ (2) ) configured to manipulate classical and / or quantum optical pulses 1802 having pulse lengths, measured in terms of a classical field value (e.g., an electric, magnetic, or electromagnetic field value) or a quantum wave function full width at half maximum, less than 1000 optical cycles 1804, respectively, and at least generating a quantum state 104, 104a, 104b, 1804 conveyed in one or more optical pulses; Measure one or more quantum states, or Measure one or more quantum states.

[0106] (2) The circuit of embodiment (1) (e.g., as shown in FIG. 7 ), wherein the width W and height H of the waveguide are each less than 5 μm, and / or the waveguide has nonlinear interaction phase matching and / or dispersion engineering of optical pulses with a bandwidth in the range of 0.1 to 100 terahertz.

[0107] (3) Figures 1D, 17, 18, 19, 23 and 24 are diagrams showing examples of circuits according to embodiment (1) or embodiment (2); one or more of the waveguides comprises an optical parametric amplifier; and / or the circuit comprises an optical parametric oscillator including one of the waveguides; and The OPA or OPO uses a second-order parametric process to generate a quantum state comprising a signal pulse and / or an idler pulse in response to a pump pulse.

[0108] (4) FIG. 1D is a diagram showing an example of a circuit according to any one of Examples (1) to (3), comprising a Gaussian state 104 that includes a squeezed vacuum state that includes one or more modes.

[0109] (5) FIG. 1D is a diagram showing an example of a circuit of embodiment (4), wherein the waveguide comprises at least the following: An optical parametric amplifier (squeezer OPA in FIG. 1D ) with phase matching and dispersion engineering for a second-order parametric amplification process including a first pump pulse (Pump 1 in FIG. 1D ) that amplifies a signal vacuum field in a first quadrature phase 105 and attenuates the signal vacuum field in a second quadrature phase that is orthogonal to the first quadrature phase, thereby generating one or more signal pulses conveying one of the first quantum states including the squeezed vacuum state 104 a.

[0110] (6) FIG. 1D further illustrates an example of the circuit of embodiment (5), where at least one of the intensity of the first pump pulse (Pump 1), phase matching, dispersion engineering, or the length L of the optical parametric amplifier is adapted for a second-order parametric amplification process with non-degenerate parametric amplification, whereby the signal pulse conveying the squeezed vacuum state 104a comprises two modes.

[0111] (7) FIG. 1D further illustrates an example of the circuit of embodiment (5) or embodiment 6, further comprising a second OPA (measurement OPA of FIG. 1D ), the second OPA having at least one of an additional second-order nonlinear interaction, a second phase matching, a second dispersion engineering, or a second length L, with a second pump pulse (pump 2 of FIG. 1D ) and a signal pulse including one of the first quantum states, the second pump pulse can have a phase difference and intensity relative to the first pump pulse, whereby the additional second-order nonlinear interaction comprises a parametric amplification (e.g., in the linear (non-saturation) region) that amplifies the quadrature phase 105 of one of the first quantum states 104a, forming a second quantum state 104b in the macroscopic region such that the average number of photons in the state is greater than 10 and is 10^9, for example, thereby enabling a loss-tolerant (decoherence-tolerant) quantum measurement of one of the first quantum states. In one or more examples, a coupler 106 (shown in FIG. 1D) for coupling the quantum state 104a to the second OPA can be placed between the first OPA and the second OPA.

[0112] (8) FIG. 18 is a diagram showing an example of a circuit of any of Examples (1) to (3), in which the quantum state comprises a non-Gaussian state 1804, the non-Gaussian state including one or more cat states, one or more Gottesman-Kitaev-Preskill (GKP) states, or one or more photon pair states. (9) FIG. 18 is a diagram showing an example of a circuit of any of Examples (1) to (8), the circuit including a modulator (e.g., the EOM of FIG. 18) driven by a drive signal that allows control of the phase or intensity of optical pulses including one or more pump pulses or one or more quantum state pulses. (10) FIG. 18 is a diagram showing an example of a circuit according to any one of the embodiments (1) to (3) or (9); The circuit 1800 comprises one or more optical parametric amplifiers (e.g., SOPA of FIG. 18 ) with phase matching, dispersion engineering, and length L adapted for second-order parametric interactions including a pump pulse 1803 with a pulse length 1804, and a vacuum field; and The second-order nonlinear interaction comprises parametric amplification in a saturation regime characterized by a suppression of the pump energy of the pump pulse 1803 by approximately 10% through the parametric amplification; and This forms a signal pulse that conveys at least one quantum state in which the Wigner function takes a negative value.

[0113] (11) FIG. 18 further illustrates an example of a circuit of any of embodiments (1) to (3), (4), (8), or (10), comprising one or more components for manipulating one or more quantum states, the one or more components comprising: one or more modulators (e.g., the EOM of FIG. 18 ) that manipulate the intensity or phase of the quantum state; one or more couplers that combine multiple quantum states (e.g., BS1, BS2 in FIG. 18), or one or more spectral filters, one or more spectrally dependent splitters, one or more polarization rotators, or one or more Mach-Zehnder interferometers (e.g., 1806 in FIG. 18 ); At least one of the following is provided.

[0114] (12) FIG. 18 illustrates an example of the circuit of any of embodiments (1)-(3), (4), (8), or (10), further including one or more detectors 1808, one or more single photon detectors, one or more photon number resolved detectors, and / or one or more homodyne detectors; Designing or detecting a quantum state 1804; or The quantum state is configured to at least enable a quantum computing task using the quantum state, such as, but not limited to, performing quantum logic gates, including, but not limited to, squeezing gates, rotation gates, phase space displacements, and the like. In one or more examples, OPAs operating in the linear (non-saturated) region in conjunction with linear circuits (MZI, EOM) enable full Gaussian logic gates (squeezing gates, rotation gates, phase space displacements). In one or more examples, such OPAs can be used in the high saturation region to perform universal quantum computation with error correction.

[0115] (13) FIG. 17 illustrates an example of a circuit 1700 of any of Examples 1-12, further comprising: one or more inputs 1702 coupled to a waveguide 1704; and one or more outputs 1706 coupled to the waveguide 1704, where the optical pulses include one or more input pulses and one or more output pulses output from the outputs in response to the input pulses received at the inputs; and the waveguide is configured to at least generate, manipulate or measure, according to a time division multiplexing scheme, one or more optical pulses carrying different quantum states 104, 1804 representing different bits of information; the light pulses are distributed among different equally spaced time bins; The different equally spaced time bins can be routed to different ones of the waveguides 1704 using one or more first modulators (e.g., EOM of FIG. 17) and one or more first couplers 1708 interconnected via one or more delay lines 1710 (e.g., properly or suitably configured delay lines), the one or more first modulators configured to modulate optical pulses, and, optionally, The different evenly spaced time bins can be combined using one or more second couplers 1708 and one or more second delay lines 1710 (e.g., properly or appropriately configured delay lines) to combine the quantum states of the different time bins. In one or more examples, the time bins are routed using time division multiplexing circuitry. (14) A circuit as described in any of Examples 1 to 13, having a pulse length 1804 in the range of 1 to 1000 femtoseconds, e.g., a duration of 1 to greater than 1000 femtoseconds, allowing optical pulses containing different bits to be routed to different equally spaced time bins.

[0116] (15) configured as a quantum processor 1712 (e.g., as shown in FIG. 17 ) that performs one or more quantum computations (e.g., quantum logic gates) on one or more quantum states; or configured as a quantum sensor 1902 (e.g., as shown in FIG. 19 ) that performs quantum sensing through measurement of one or more quantum states; or configured to perform quantum state tomography of the quantum states 2302, 2403 that is robust to detection losses (e.g., as shown in Figures 23 and 24); or configured to perform all-optical continuously variable quantum error correction with binomial and squeezed cat codes using the quantum states 1804; or configured to perform quantum teleportation using the quantum state; or configured to perform boson sampling in the time / frequency domain using the quantum state; or configured to preserve quantum coherence of the quantum state; The circuit according to any one of the first to fourteenth embodiments. (16) The circuit according to any one of the embodiments (1) to (16), wherein the waveguide 102 comprises an optical parametric amplifier, the optical parametric amplifier having phase matching and dispersion engineering such that the parametric gain is in the nonlinear saturation region, and thus the waveguide is F All-optical nonlinear quantum measurements of quantum states (e.g., Figs. 1D, 18, 23, 24), or Nonlinear or non-Gaussian manipulation of quantum states (e.g., Figure 18) At least one of the following is possible.

[0117] (17) The circuit according to any one of the embodiments (1) to (16), further comprising a wavelength converter, which converts the wavelength of the optical pulse into a different wavelength range and transmits the quantum state into the different wavelength range. (18) The circuit according to any one of the embodiments (1) to (17), wherein the optical pulse is Pulses of electromagnetic radiation with a center in the range of 200 nm to 10 microns, Pulse lengths of 1000 cycles or less, or pulse lengths corresponding to 1000 wavelengths or less, or pulse lengths corresponding to 1000 wavelengths or less of a classical or quantum mechanical wave function, respectively.

[0118] (19) The circuit according to any one of the embodiments (1) to (18), The waveguide comprises / consists of / consists essentially of a material having second-order nonlinearity, the material being / comprising / consisting of / consisting essentially of at least one of lithium niobate, lithium tantalate, potassium titanyl phosphate (KTP), aluminum nitride, gallium arsenide, indium phosphide, aluminum gallium arsenide, GaP, or InGaP. (20) The circuit according to any one of the embodiments (1) to (19), wherein the width and / or height of the waveguide is in the range of 50 nanometers to 5 micrometers. (21) The circuit according to any one of the embodiments (1) to (20), wherein the waveguide confines and guides an optical pulse, the optical pulse comprising a pump electromagnetic wave or field (pump pulse), a signal electromagnetic wave or field (signal pulse), and / or an idler electromagnetic wave or field (idler pulse), and the pump electromagnetic wave is converted into the signal electromagnetic wave and / or the idler electromagnetic wave according to second-order parametric interaction / second-order parametric amplification using second-order nonlinearity. (22) The circuit according to any one of embodiments (1) to (21), wherein the waveguide has dimensions including length, width, and length that minimizes group velocity mismatch (GVM) between the pump pulse and the signal pulse, and / or between the pump pulse and the idler pulse, and is configured such that the pump pulse and the signal pulse, and / or the pump pulse and the idler pulse overlap in time. (23) The circuit according to any one of the embodiments (1) to (22), wherein the length of the waveguide is in the range of 10 microns to 1 mm, e.g., resulting in a GVM difference of less than 1%. (24) FIG. 2A illustrates an exemplary system 200 including the circuit of any of Examples 1 to 23, the system further including: one or more sources 202 of optical pulses (e.g., lasers, optical parametric generators, optical parametric amplifiers, optical parametric oscillators, or laser systems) coupled to the circuit, the circuit comprising: one or more inputs 204 for receiving optical pulses comprising a pump signal to pump the waveguide; and One or more outputs 206 output optical pulses conveying the quantum states. In one or more embodiments, the waveguide includes a measurement optical parametric amplifier that amplifies the quantum states to a detectable level. (25) The circuit according to any one of the embodiments (1) to (24), wherein the phase matching comprises a periodic polarization of the waveguide (or a material of the waveguide having second-order nonlinearity, e.g., a ferromagnetic material). (26) FIG. 19 illustrates an exemplary quantum sensor system comprising a circuit 1900 according to any of the compatible Examples 1-25, the circuit comprising a waveguide comprising a squeezer optical parametric amplifier that outputs one or more quantum states to one or more first linear optical components (e.g., one or more splitters and / or one or more couplers or one or more interferometers), the waveguide outputs the quantum states to a sample / environment for interaction, and one or more second linear optical components (e.g., one or more splitters and / or couplers or interferometers) receive the output quantum states and transmit and / or manipulate the output quantum states to a measurement optical parametric amplifier to form one or more output quantum states. (27) FIG. 17 illustrates an example circuit that includes a pair of state generating (e.g., squeezer) optical parametric amplifiers 1704 that output quantum states including a first (e.g., squeezed) quantum state and a second (e.g., squeezed) quantum state, and a first coupler / splitter 1708 that couples the pair of (e.g., squeezer) OPAs and couples / interacts the first quantum state with the second quantum state, the circuit comprising: a modulator (e.g., an electro-optic modulator EOM) coupled to at least one of the optical parametric amplifiers 1704 (e.g., a squeezer) that modulates the phase or amplitude of the first or second quantum state; a delay line 1710 coupled to one or more outputs of the first coupler 1708; a second coupler coupled to the first coupler via one or more delay lines 1710; and a pair of measurement optical parametric amplifiers 1714 coupled to a second coupler; each measurement optical parametric amplifier is coupled to one of the different outputs of the second coupler and amplifies one of the quadrature phases 105 of one of the quantum states generated or manipulated in the circuit to form an output quantum state of the macroscopic domain. (28) FIG. 18 illustrates an example circuit comprising first and second state generating optical parametric amplifiers 1801, which generate first and second quantum states, respectively (e.g., amplitude and phase squeezed states, respectively), and the circuit includes: a modulator (e.g., an EOM) coupled to at least one of the state generating optical parametric amplifiers to modulate the phase and / or amplitude of the quantum state; a coupler or splitter BS1 for interacting the first and second quantum states; an interferometer 1806 interfering with the output of the coupler or splitter BS1, and a plurality of measurement optical parametric amplifiers (MOPAs) coupled to the output of the interferometer that amplify one of the quadratures 105 of the quantum states generated or manipulated in the circuit (e.g., in the macroscopic domain) to form one or more output quantum states; By tuning the interferometer and post-selecting specific photon-number resolved measurements, output quantum states comprising non-Gaussian states can be probabilistically generated. (29) FIG. 23 is an example of a circuit that includes a quantum tomography circuit 2300, the quantum tomography circuit having a first input that receives a quantum state ρ; a second input receiving JPEG2025501863000103.jpg1183, and a highly unbalanced beam splitter, i.e., r→1, the quantum tomography circuit comprising a step of performing a displacement operation on the quantum state having a coherent state to form an output quantum state, and a waveguide comprising an optical parametric amplifier coupled to the output of the splitter / coupler, the optical parametric amplifier amplifying the output quantum state output from the output of the splitter / coupler. (30) FIG. 24 shows an example of a circuit comprising a quantum tomography circuit 2400, the quantum tomography circuit comprising a first input for receiving a quantum state psi, a wavelength division multiplexer WDM for combining the pump and the quantum state in a high gain parametric amplifier forming one of the waveguides, and a photodetector for performing a quadrature power measurement on the amplified state. (31) Any of the circuits of the embodiments, coupled to linear optical components (e.g., beam splitters, splitters, mirrors, phase shifters, lenses, interferometers) to perform, for example, a linear operation on optical pulses (i.e., following the principle of superposition, and not a nonlinear interaction that changes frequency). (32) A circuit according to any one of the embodiments, wherein the quantum state includes a squeezed amplitude state and a squeezed phase state. (33) A single chip or multiple chips comprising the circuit according to any one of the embodiments (1) to (32). (34) For example, a processor 1712 or processing circuit comprising a photonic integrated circuit 1700 according to any one of embodiments (1) to (34), wherein the circuit performs or is configured to perform a quantum computation using a quantum state. (35) For example, a quantum sensor 1902 or a quantum sensing circuit comprising a photonic integrated circuit 1900 according to any one of Examples (1) to (33), which senses or is configured to sense an environment or a sample using a quantum state. (36) An error correction circuit comprising a photonic integrated circuit according to any of the embodiments, the circuit performing or configured to perform error correction using quantum states. (37) A quantum tomography circuit 2300, 2400 comprising a photonic integrated circuit according to any of the embodiments, the circuit performing or configured to perform quantum tomography of one or more quantum states. (38) FIG. 17 shows a processor 1712 or processing circuit 1700 including a photonic integrated circuit according to the first embodiment or a compatible photonic integrated circuit according to any of the first to third embodiments, the processor or processing circuit being: a waveguide 1704 for generating one or more quantum states; and One or more logic gates comprising one or more waveguides that perform one or more logical operations on one or more quantum states Equipped with. (39) FIG. 19 shows a quantum sensor 1902 or quantum sensing circuit comprising the photonic integrated circuit of Example 1 or any of the compatible photonic integrated circuits of Examples (2) to (33), the quantum sensor or quantum sensing circuit comprising: One or more waveguides (squeezer OPAs) generate one or more quantum states that are used to sense the environment (e.g., sample interactions); and One or more waveguides (eg, measurement OPAs) measure one or more quantum states after interaction with the environment. (40) An error correction circuit comprising or coupled to the photonic integrated circuit of embodiment 1 or any of the compatible photonic integrated circuits of embodiments (2) to (33), the circuit comprising: One or more waveguides (e.g., SOPAs) generate quantum states 1804 useful for performing quantum error correction of quantum noise (see, e.g., FIG. 18 ); and A circuit, the circuit performing, or configured to perform, quantum error correction using a quantum state.

[0119] (41) Figures 23A and 24 show quantum tomography circuits 2300, 2400 comprising a photonic integrated circuit compatible with any of embodiment (1) or embodiment (2) to embodiment (33), the quantum tomography circuit implementing the quantum tomography circuit in one or more quantum states. (42) A circuit according to any one of embodiments (1) to (41), wherein one or more of the waveguides are provided with an optical parametric amplifier, and / or the circuit further comprises one or more optical parametric oscillators provided with one or more of the waveguides. (43) The circuit of embodiment (42) comprising a network of waveguides. (44) The circuit 1700 according to any of the embodiments (1) to (43), wherein the circuit is coupled to or comprises a time division multiplexing circuit 1716, e.g., the time division multiplexing circuit (e.g., comprising a coupler and / or a delay line and / or a modulator) for routing time bins to different waveguides 1714 and / or combining different time bins together (e.g., as illustrated in FIG. 17). Examples of time division multiplexing architectures that can be used include those of

[52] . (45) A circuit according to any one of embodiments (1) to (44), wherein the dimensions of the waveguide minimize group velocity dispersion (GVD) of the interacting pulses, resulting in high nonlinear efficiency. (46) The circuit of any one of embodiments (1) to (45), wherein the coupler or splitter comprises a pair of waveguides separated by a gap. In one or more embodiments, the coupler or splitter has superselectivity or coupling sensitivity tuned by a gap size between the single waveguides

[54] . (47) The circuit of any of the embodiments, wherein the linear optics comprises a splitter, a coupler, an interferometer, or a delay line. b.How to operate FIG. 27 illustrates a method for processing one or more quantum states. Block 2700 inputs one or more input optical pulses into one or more waveguides, the waveguides having a second-order nonlinearity configured to manipulate the optical pulses (including the input optical pulses), the waveguides each having a width and height less than 5 μm, and / or the waveguides having optical pulse phase matching and dispersion engineering for a bandwidth in the range of 0.1 to 100 THz.

[0120] Block 2702 represents generating, manipulating, or measuring one or more quantum states using one or more waveguides. In one or more embodiments, the generating, manipulating, or measuring may be implemented in a time multiplexed scheme, such that the generating, manipulating, or measuring may be implemented in a time multiplexed scheme, such as: Distributing the optical pulses among equally spaced time bins; Routing the time bins to different ones of the waveguides using one or more modulators and one or more first couplers, each connected to one another via one or more first delay lines; and combining the different time bins using one or more second couplers and one or more second delay lines such that quantum states of the different time bins are combined; Equipped with. The method may be performed using the apparatus of any of the embodiments described herein, including embodiments 1-47 described above in connection with FIG. Advantages and Improvements The data presented here demonstrate several cycles of vacuum squeezing and its all-optical measurement in a LN nanophotonic platform. On-chip, all-optical, loss-tolerant broadband measurements with high-gain phase-sensitive amplification enable squeezing measurements with bandwidths of over 25 THz, while We achieve a measurement accuracy for detection losses as high as 1032. Combined with recent advances such as high-speed electro-optic modulators and integrated single-photon detectors, (23) these results may enable scalable ultrafast all-photonic quantum information processors with second-order nonlinearity integrity in nanophotonic platforms.

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[0122] [Conclusion] This completes the description of the preferred embodiments of the present invention. The foregoing description of one or more embodiments of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teachings. It is intended that the scope of the invention be limited not by this detailed description, but rather by the appended claims.

Claims

1. 1. A photonic integrated circuit comprising one or more waveguides including a second-order nonlinearity, the waveguides configured to act on classical and / or quantum optical pulses, the classical and / or quantum optical pulses having a pulse length, measured at full width at half maximum of the classical field value or quantum wave function of each pulse, respectively, less than 1000 optical cycles, the waveguides comprising at least generation of one or more quantum states carried by one or more optical pulses; Manipulation of one or more quantum states, or Measuring one or more quantum states Photonic integrated circuits.

2. 10. The photonic integrated circuit of claim 1, wherein the waveguides are less than 5 μm in width and height, respectively, and / or the waveguides have phase matching and / or dispersion engineering for nonlinear interaction of optical pulses with a bandwidth in the range of 0.1 to 100 THz.

3. the one or more waveguides comprise an optical parametric amplifier (OPA); and / or the photonic integrated circuit comprises an optical parametric oscillator (OPO) including one of the waveguides; the OPA or the OPO generates the quantum state including a signal pulse and / or an idler pulse in response to a pump pulse using a second-order parametric process; the waveguides are configured such that dimensions including the height, the width, and the length minimize a velocity mismatch (GVM) between the pump pulse and the signal pulse and / or the pump pulse and the idler pulse, respectively, such that the pump pulse and the signal pulse and / or the pump pulse and the idler pulse overlap in time; The photonic integrated circuit of claim 2 , wherein the pump pulse, the signal pulse and / or the idler pulse comprise electromagnetic waves that are confined and guided within respective waveguides.

4. The photonic integrated circuit of claim 1 , wherein the quantum states include Gaussian states, each Gaussian state including a squeezed vacuum state having one or more modes.

5. The waveguide includes at least an optical parametric amplifier including phase matching and / or dispersion engineering for a second-order parametric amplification process involving a first pump pulse and a vacuum signal field; 5. The photonic integrated circuit of claim 4, wherein the second order parametric amplification process amplifies the vacuum signal field in a first quadrature and attenuates the vacuum signal field in a second quadrature that is orthogonal to the first quadrature, thereby generating one or more signal pulses conveying one of a first quantum state comprising a vacuum squeezed state.

6. 6. The photonic integrated circuit of claim 5, wherein at least one of the intensity of the first pump pulse, the phase matching, the dispersion engineering, or the length of the optical parametric amplifier is adapted for a second order parametric amplification process involving a non-degenerate parametric amplifier, whereby the signal pulse conveying the squeezed vacuum state comprises at least two modes.

7. 6. The photonic integrated circuit of claim 5, further comprising a second OPA having at least one of a second phase matching, a second dispersion engineering, or a second length tuned for an additional second-order nonlinear interaction with a second pump pulse and a signal pulse including the first quantum state, the second pump pulse having a phase difference and intensity relative to the first pump pulse such that the additional second-order nonlinear interaction can include the parametric amplification in a linear (non-saturated) regime that amplifies one of the quadrature phases of the first quantum state, forming a second quantum state in a macroscopic regime, in which the average photon number of a quantum state is greater than 10 and less than 10^9, thereby enabling a loss-tolerant (decoherence-tolerant) quantum measurement of the first quantum state.

8. 2. The photonic integrated circuit of claim 1, wherein the quantum states include non-Gaussian states, each non-Gaussian state including one or more cat states, one or more binomial code states, one or more Gottesman-Kitaev-Preskill (GKP) states, or one or more photon pair states.

9. 10. The photonic integrated circuit of claim 1, comprising a modulator driven by a drive signal that enables control of the phase or intensity of optical pulses, including one or more pump pulses or one or more quantum state pulses.

10. the photonic integrated circuit comprising an optical parametric amplifier having a phase matching, dispersion engineering, and length adapted for second order parametric interaction with a pump pulse having the pulse length and a vacuum field; the second-order nonlinear interaction includes parametric amplification in a saturation region, and a pump energy of the pump pulse is suppressed by more than 10% through the parametric amplification; The photonic integrated circuit of claim 1 , thereby forming a signal pulse conveying at least one quantum state in which the Wigner function takes a negative value.

11. The photonic integrated circuit includes one or more components for manipulating the one or more quantum states, the one or more components comprising: one or more modulators that manipulate the intensity or phase of said quantum states; A coupler that couples multiple quantum states, or one or more spectral filters, one or more spectrally dependent splitters, one or more polarization rotators, or one or more Mach-Zehnder interferometers The photonic integrated circuit of claim 1 , comprising at least one of:

12. The photonic integrated circuit includes at least Designing or detecting quantum states, or 13. The photonic integrated circuit of claim 1, further comprising one or more single photon detectors, one or more photon number resolving detectors, and / or one or more homodyne detectors configured to enable quantum computing tasks using the quantum states.

13. one or more inputs coupled to the waveguide; and One or more outputs coupled to the waveguide Further comprising: the optical pulses include one or more input pulses and one or more output pulses output from the output in response to the input pulses received at the input; the waveguide is configured at least to generate, manipulate, or measure one or more optical pulses conveying different quantum states representing different bits of information according to a time division multiplexing scheme; The light pulses are distributed among different equally spaced time bins; the different equally spaced time bins may be routed to different ones of the waveguides using one or more first modulators and one or more first couplers interconnected via one or more first delay lines; 2. The photonic integrated circuit of claim 1, wherein the different equally spaced time bins can be combined using one or more second couplers and one or more second delay lines, thereby coupling quantum states in the different time bins.

14. 14. The photonic integrated circuit of claim 13, wherein the pulse length is in the range of 1 to 1000 femtoseconds, whereby optical pulses are routed into different equally spaced time bins that have durations greater than 1 to 1000 femtoseconds and contain different bits.

15. configured as a processor to perform one or more quantum computations on one or more quantum states; or configured as a quantum sensor for performing quantum sensing by measuring said one or more quantum states; or configured to perform quantum state tomography of the quantum state that is robust to detection loss; or configured to perform all-optical continuously variable quantum error correction using binomial and squeezed cat codes using said quantum states; or configured to perform quantum teleportation using the quantum state; or configured to perform boson sampling in the time / frequency domain using the quantum state; or The photonic integrated circuit of claim 1 configured to preserve quantum coherence of a quantum state.

16. The waveguide comprises an optical parametric amplifier having phase matching and dispersion engineering such that the parametric gain is in a nonlinear saturation region, thereby providing at least an all-optical linear or nonlinear quantum measurement of said quantum state; or Gaussian or non-Gaussian The photonic integrated circuit of claim 1 ,

17. The photonic integrated circuit of claim 1 , further comprising a wavelength converter that converts the wavelength of the optical pulses conveying the quantum state to a different frequency range.

18. inputting one or more input optical pulses into one or more waveguides; generating, manipulating, or measuring one or more quantum states using one or more waveguides including a second-order nonlinearity configured to operate on optical pulses including the input pulse, each having a width and height less than 2 μm and / or a bandwidth in the range of 0.1 to 100 terahertz, and A method for processing one or more quantum states, comprising:

19. The generating, manipulating, or measuring is performed using a time division multiplexing scheme, the method comprising: distributing said light pulses among equally spaced time bins; routing the time bins to different ones of the waveguides using one or more modulators and one or more first couplers, each coupled to one another via one or more first delay lines; combining the different time bins using one or more second couplers and one or more second delay lines such that the quantum states of the different time bins are combined; 20. The method of claim 18, wherein the waveguide comprises one or more optical parametric amplifiers and / or the waveguide is disposed in one or more optical parametric oscillators.

20. The generating, manipulating, and / or measuring includes: performing one or more quantum computations on the one or more quantum states; performing quantum sensing by measuring said one or more quantum states; or performing quantum state tomography of said quantum state that is robust to detection loss; and performing all-optical continuously variable quantum error correction with binomial and squeezed cat codes using said quantum state. performing quantum teleportation using said quantum state; Performing boson sampling in the time / frequency domain with quantum states; or 20. The method of claim 18, comprising at least one of: preserving quantum coherence of the quantum state.

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