Quantum chip

Abstract

The present disclosure provides a quantum chip, comprising: a qubit configured to generate an electrical signal; and an electro-optical modulator electrically connected to the qubit and configured to modulate, on the basis of the electrical signal input from the qubit, an optical signal transmitted in the electro-optical modulator, so that the optical signal carries qubit information generated by the qubit. The quantum chip of the present disclosure combines a qubit with an electro-optical modulator and, by utilizing the high-speed response characteristics of the electro-optical modulator, uses the electrical signal generated by the qubit to promptly modulate the optical signal in the electro-optical modulator, so that the electrical signal generated by the qubit can be transmitted in the form of an optical signal. The quantum chip of the present disclosure has the advantages of high transmission speed, low attenuation, strong anti-interference capability, and high signal-to-noise ratio.

Description

A quantum chip Technical Field

[0001] This disclosure relates to the field of quantum computing, and more particularly to a quantum chip. Background Technology

[0002] In the field of quantum computing, superconducting quantum chips play a crucial role. These chips typically operate at extremely low temperatures. However, this extreme environment presents significant challenges to signal transmission. Currently, signal transmission is primarily achieved via microwave cables.

[0003] A combination of a dilution refrigerator and microwave cables is used in testing superconducting quantum chips. The dilution refrigerator provides an extremely low-temperature testing environment, achieved through a multi-stage cooling structure. The microwave cables at the signal input, control, and readout ends traverse different temperature ranges. At the signal input, the electrical signal at room temperature passes through the cable and attenuator to reduce interference, but signal attenuation still occurs. At the signal output, the cable also contributes to signal attenuation. To reduce signal attenuation across different temperature ranges, different types of signal amplifiers are used to enhance the signal and improve the signal-to-noise ratio. However, this approach increases system complexity and may introduce noise.

[0004] In contrast, optical fibers, as carriers of optical signals, have advantages such as low attenuation loss and strong anti-interference ability. However, currently, optical fibers and signal modulators are generally suitable for operation at room temperature (-40℃ to 80℃), which is not suitable for the extremely low temperature environment of superconducting quantum chips. How to overcome the inability of existing optoelectronic devices to be used in quantum chips has become a major problem. Summary of the Invention

[0005] This disclosure proposes a quantum chip that utilizes the characteristics of optical fiber, such as low loss, strong anti-interference ability, large data throughput, and large bandwidth, as well as the fact that the electro-optic modulator can operate at extremely low temperatures and has low power consumption, thereby improving the efficiency and quality of signal transmission in the quantum chip.

[0006] To achieve the above objectives, this disclosure provides a quantum chip, comprising:

[0007] Quantum bits are configured to generate electrical signals;

[0008] An electro-optic modulator, electrically connected to the qubit, configured to modulate an optical signal transmitted in the electro-optic modulator based on an electrical signal input to the qubit, so that the optical signal carries qubit information generated by the qubit.

[0009] Optionally, the quantum chip also includes a base plate, which has a first region, a second region, and a first pad. The first pad is disposed at the edge of the base plate and surrounds the first region and the second region. The first region is configured to fix the quantum bit, the second region is configured to fix the electro-optic modulator, and the first pad is configured to electrically connect the quantum bit and the microwave cable.

[0010] Optionally, the electro-optic modulator is further provided with a ceramic shell, which is configured to cover and seal the electro-optic modulator to avoid interference of the electro-optic modulator with the quantum bit.

[0011] Optionally, the electro-optic modulator includes:

[0012] An input optical fiber is configured to input the optical signal.

[0013] A beam splitter, which is connected to the input optical fiber, is configured to split the optical signal into beams;

[0014] An electro-optic modulation structure, connected to the beam splitter, is configured to modulate the phase of an optical signal from the beam splitter;

[0015] A beam combiner, which is connected to the electro-optic modulation structure, interferes with the optical signal from the electro-optic modulation structure;

[0016] An output optical fiber is connected to the combiner and outputs an optical signal from the combiner.

[0017] Optionally, the electro-optic modulation structure includes at least one pair of modulation arms, which can be connected in parallel or cascaded.

[0018] Optionally, there are multiple electro-optic modulators, and the multiple electro-optic modulators surround the quantum bit on the substrate.

[0019] Optionally, each pair of modulation arms is provided with a pair of signal electrodes and a ground electrode with opposite electric field directions.

[0020] Optionally, the electro-optic modulator includes:

[0021] Substrate;

[0022] An optical waveguide layer is disposed on a substrate;

[0023] An electro-optic modulation layer is disposed on the optical waveguide layer.

[0024] Optionally, the coupling method between the electro-optic modulation layer and the input optical fiber and / or the coupling method between the electro-optic modulation layer and the output optical fiber includes any one of end-face coupling, optical fiber beveling, micromirror, focusing grating coupling, lens fiber, chip flip-chip, and photonic interposer.

[0025] Optionally, the output optical fiber and the input optical fiber are capable of transmitting the optical signal at a 4K temperature.

[0026] The beneficial effects of this disclosure include:

[0027] In this quantum chip, qubits are combined with an electro-optic modulator. By utilizing the high-speed response characteristics of the electro-optic modulator, the electrical signal generated by the qubits is used to modulate the optical signal in the electro-optic modulator in a timely manner, so that the electrical signal generated by the qubits can be transmitted in the form of an optical signal. The quantum chip disclosed in this paper has the advantages of fast transmission speed, low attenuation, strong anti-interference ability, and high signal-to-noise ratio.

[0028] The ceramic shell on the outside of the electro-optic modulator can prevent the electro-optic modulator from interfering with the quantum bits and also protect the electro-optic modulator.

[0029] Quantum chips can be designed with reasonable electro-optic modulation structures and the number and arrangement of electro-optic modulators based on qubits, making the internal device structure of the quantum chip compact. This helps to reduce the area occupied by the internal devices of the quantum chip and the size of the quantum chip, and also reduces the difficulty of lead layout in the quantum chip, so as to facilitate the construction of complex quantum computing systems.

[0030] Quantum chips use optical fibers for coupling and signal transmission, which features low loss, strong anti-interference ability, large data throughput, and large bandwidth. Furthermore, the electro-optic modulator and optical fiber can operate at extremely low temperatures, which helps to improve the signal-to-noise ratio and enhances the efficiency and quality of signal transmission in quantum chips. Attached Figure Description

[0031] Figure 1 is a schematic diagram of the structure of the quantum chip disclosed herein;

[0032] Figure 2 is a three-dimensional structural schematic diagram of the single-channel signal modulation electro-optic modulator of this disclosure;

[0033] Figure 3 is a schematic diagram of the structure of the electro-optic modulator with parallel structure of multi-channel signal modulation disclosed in this invention;

[0034] Figure 4 is a schematic diagram of the structure of the cascaded multi-channel signal modulation electro-optic modulator of this disclosure;

[0035] Figure 5 is a schematic diagram of the structure of the quantum chip with multiple electro-optic modulators disclosed herein;

[0036] Figure 6 is a schematic diagram of the bent modulation arm of the single-channel signal modulation electro-optic modulator of this disclosure;

[0037] Figure 7 is a schematic cross-sectional view of the electro-optic modulator with single-channel signal modulation disclosed herein.

[0038] Figure 8 is a schematic diagram of the pattern conversion structure disclosed herein.

[0039] In the diagram: 1. Quantum bit; 2. Electro-optic modulator; 3. Base plate; 41. First pad; 42. Second pad; 43. Third pad; 5. Microwave cable; 6. Ceramic shell; 7. Input fiber; 8. Output fiber; 21. Electro-optic modulation structure; 22. Beam splitter; 23. Beam combiner; 211. First modulation arm; 212. Second modulation arm; 213. Substrate; 214. Optical waveguide layer; 215. Electro-optic modulation layer; 216. Signal electrode; 217. Ground electrode. Detailed Implementation

[0040] The technical solutions of this disclosure will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this disclosure.

[0041] To make the above-mentioned objectives, features and advantages of this disclosure more apparent and understandable, the disclosure will be further described in detail below with reference to specific embodiments.

[0042] In existing technologies, superconducting quantum chips operate in extremely low-temperature environments and transmit signals via microwave cables. However, microwave cables experience significant signal attenuation when passing through different temperature ranges.

[0043] To address the aforementioned problems, this disclosure provides a quantum chip, including a qubit 1 configured to generate an electrical signal; and an electro-optic modulator 2 electrically connected to the qubit 1, configured to modulate an optical signal transmitted in the electro-optic modulator 2 based on the electrical signal input to the qubit 1, so that the optical signal carries the qubit information generated by the qubit 1. For example, the quantum chip may include multiple qubits 1 coupled together and configured to generate electrical signals.

[0044] In this quantum chip, qubit 1 is combined with an electro-optic modulator 2. Utilizing the high-speed response characteristics of the electro-optic modulator 2, the electrical signal generated by qubit 1 is used to modulate the optical signal in the electro-optic modulator in real time, enabling the electrical signal generated by qubit 1 to be transmitted in the form of an optical signal. This disclosed quantum chip has advantages such as high transmission speed, low attenuation, strong anti-interference capability, and high signal-to-noise ratio. Simultaneously, the optical signal, as the carrier of quantum information, is difficult to steal or tamper with during transmission, which helps to enhance the security of quantum information transmission.

[0045] In some embodiments of this disclosure, as shown in Figure 1, this disclosure provides a quantum chip, including a qubit 1 and an electro-optic modulator 2. A qubit is the basic unit in a quantum computer, possessing superposition and entanglement properties, enabling it to process and transmit information, and allowing the construction of quantum computers that are more powerful and efficient than classical computers. Compared to classical computers, the superposition property of qubits allows quantum computers to process many tasks simultaneously, greatly improving computational speed, while the entanglement property enables quantum computers to achieve more secure and efficient communication and computation. The types of qubits can be, but are not limited to, superconducting qubits, ion trap qubits, photonic qubits, spin qubits, topological qubits, etc. In the quantum chip of this disclosure, qubit 1 can be installed and configured multiple times, and different qubits 1 can be installed each time.

[0046] Quantum bit 1 generates electrical signals under specific conditions (such as excitation or measurement by external magnetic, electric, or optical fields). These electrical signals are a manifestation of the qubit's state and can reflect the properties or information of qubit 1. As carriers of quantum information, these electrical signals transmit information within the quantum chip or between other quantum chips. The electrical signals can be configured to control the state of qubit 1 or perform quantum logic operations, thereby enabling the processing of quantum information.

[0047] Electro-optic modulator 2 is an optical device that modulates the phase, amplitude, or polarization state of light by changing the refractive index of a medium using an applied electric field. It is based on the electro-optic effect; when an electric field is applied to an electro-optic crystal, the crystal's refractive index changes, thereby causing a change in the characteristics of the light waves passing through the crystal, achieving modulation of the phase, amplitude, intensity, and polarization state of the optical signal. Electro-optic modulator 2 can be of various types, including but not limited to phase electro-optic modulators, intensity electro-optic modulators, polarization electro-optic modulators, FP-type electro-optic modulators, Si-based electro-optic modulators, Michelson interferometer electro-optic modulators, resonant cavity electro-optic modulators, and Z-cut lithium niobate electro-optic modulators.

[0048] Based on the characteristics and working principle of the aforementioned qubit 1 and electro-optic modulator 2, the electro-optic modulator 2 is electrically connected to the qubit 1 in the quantum chip. The qubit 1 is configured to generate an electrical signal, and the electro-optic modulator 2 is configured to modulate the optical signal transmitted in the electro-optic modulator 2 based on the electrical signal input from the qubit 1, so that the optical signal carries the qubit information generated by the qubit 1.

[0049] When qubit 1 generates an electrical signal, the signal is input into electro-optic modulator 2. Electro-optic modulator 2 modulates the transmitted optical signal based on the input electrical signal, giving the optical signal the information generated by qubit 1. The optical signal modulated by electro-optic modulator 2 carries the information of qubit 1. These optical signals can be used for the transmission, processing, or storage of quantum information.

[0050] Therefore, in the quantum chip disclosed herein, qubit 1 is combined with electro-optic modulator 2. By utilizing the high-speed response characteristics of electro-optic modulator 2, the electrical signal generated by qubit 1 is used to modulate the optical signal in electro-optic modulator 2 in a timely manner, so that the electrical signal generated by qubit 1 can be transmitted in the form of optical signal. The quantum chip disclosed herein has advantages such as fast transmission speed, low attenuation, strong anti-interference ability, and high signal-to-noise ratio.

[0051] In some embodiments of this disclosure, the quantum chip may contain multiple qubits 1, which are coupled to each other and configured to generate electrical signals. An electro-optic modulator 2 is electrically connected to the multiple qubits 1 and configured to modulate the optical signal transmitted in the electro-optic modulator 2 based on the electrical signals input to the multiple qubits 1, so that the optical signal carries the qubit information generated by the multiple qubits 1. The multiple qubits 1 may include 8 qubits, 12 qubits, 16 qubits, 20 qubits, 100 qubits, 200 qubits, etc.; and the shape of the qubits 1 may include a cross shape, a star shape, etc. This disclosure does not limit the number or shape of the qubits 1.

[0052] In some embodiments of this disclosure, as shown in FIG1, the quantum chip further includes a base plate 3. The base plate 3 is provided with a first region, a second region, and a first pad 41. The first pad 41 is disposed at the edge of the base plate 3 and surrounds the first and second regions. The first region corresponds to the location of the quantum bit 1 and is configured to fix the quantum bit 1. The second region corresponds to the location of the electro-optic modulator 2 and is configured to fix the electro-optic modulator 2. The first pad 41 is configured to electrically connect the quantum bit 1 and the microwave cable 5. For example, the quantum bit 1 and the electro-optic modulator 2 are also provided with a second pad 42 and a third pad 43, respectively. The second pad 42 surrounds the quantum bit 1, and the third pad 43 surrounds the electro-optic modulator 2. The second pad 42 and the third pad 43 are wire-bonded to electrically connect the quantum bit 1 and the electro-optic modulator 2. The first pad 41 and the second pad 42 are also wire-bonded to electrically connect the quantum bit 1 and the first pad 41.

[0053] This disclosure effectively improves the integration and stability of quantum chips. By placing the first pad 41 on the edge of the base plate 3 and surrounding the area where the qubits and electro-optic modulator are located, not only is the wiring structure optimized, but electromagnetic interference is also reduced. The application of the second pad 42, the third pad 43, and the wire bonding process makes the quantum chip structure compact and does not introduce additional impedance matching devices.

[0054] Microwave cable 5 transmits external control signals to quantum bit 1 for control and operation of quantum bit 1. Microwave cable 5 includes quantum bit drive lines, coupler drive lines, and signal lines.

[0055] In some embodiments of this disclosure, the qubit driving line includes an XY line and a Z line. Specifically, the XY line is configured to drive qubit 1 and control its state. Microwave signals are transmitted in the XY line, which can excite qubit 1 to transition between different energy levels, thereby enabling quantum information processing and computation. The Z line is configured to control the frequency of qubit 1. Magnetic flux signals or other forms of control signals are transmitted in the Z line.

[0056] In some embodiments of this disclosure, the coupler is configured to couple different qubits 1 to enable interaction and information exchange between the qubits 1. The coupler drive line is configured to transmit control signals to the coupler, thereby enabling precise control of the coupler.

[0057] In some embodiments of this disclosure, the signal lines are configured to transmit control signals and status information, ensuring information transmission between the quantum chip and an external control system.

[0058] The electro-optic modulator 2 is provided with a ceramic shell 6, which is configured to cover and seal the electro-optic modulator 2 to prevent the interference of particles and quasi-particles generated by the electro-optic modulator 2 during operation to the quantum bit 1, and also to protect the electro-optic modulator 2.

[0059] In some embodiments of this disclosure, the electro-optic modulator 2 includes an input optical fiber 7, a beam splitter 22, an electro-optic modulation structure 21, a beam combiner 23, and an output optical fiber 8. The input optical fiber 7 is configured to input an optical signal; the beam splitter 22 is connected to the input optical fiber 7 and configured to split the optical signal; the electro-optic modulation structure 21 is connected to the beam splitter 22 and configured to modulate the phase of the optical signal from the beam splitter 22; the beam combiner 23 is connected to the electro-optic modulation structure 21 and interferes with the optical signal from the electro-optic modulation structure 21; and the output optical fiber 8 is connected to the beam combiner 23 and outputs the optical signal from the beam combiner 23. The electro-optic modulation structure 21 may be a Mach-Zehnder interferometer.

[0060] As shown in Figure 2, the electro-optic modulator 2 includes an input optical fiber 7, a beam splitter 22, an electro-optic modulation structure 21, a beam combiner 23, and an output optical fiber 8. The electro-optic modulation structure 21 includes modulation arms and electrodes. The beam splitter 22, modulation arms, and beam combiner 23 are optical waveguides configured to transmit optical signals. The input optical fiber 7 guides the optical signal to the beam splitter 22, which splits the optical signal into two beams and guides them into the two modulation arms respectively. The splitting ratio of the beam splitter 22 can be 1:1; this disclosure does not limit the splitting ratio of the beam splitter. Electrodes are arranged on each modulation arm to form the electro-optic modulation structure 21. When a voltage is applied to the electrodes, the phase of the optical signal changes based on the electro-optic effect, and the two optical signals carry different phase information. These two phase-modulated optical signals are guided to the beam combiner 23, which combines the two optical signals. Due to the phase difference between the two optical signals, light interference occurs at the beam-combining point, where the phase change is related to the voltage change applied to the electrodes. The combined optical signal is output through output fiber 8, carrying the quantum bit information modulated by electro-optic modulator 2. By demodulating the optical signal output from output fiber 8, the original electrical signal applied to the electrodes can be accurately recovered, thereby improving the transmission speed of quantum bit information. Furthermore, the quantum bit information exhibits low attenuation and a high signal-to-noise ratio during transmission.

[0061] The disclosed quantum chip combines a qubit 1 with an electro-optic modulator 2 to achieve efficient conversion of electrical signals to optical signals. Optical fiber and optical waveguide, serving as the transmission medium for the optical signal, offer advantages such as high transmission speed, low attenuation, and strong anti-interference capabilities, ensuring long-distance, low-loss transmission of qubit information. The electro-optic modulator 2 uses the input optical fiber 7 to introduce the optical signal, performs beam splitting, phase modulation, and beam combining on the optical signal, and outputs the optical signal through the output optical fiber 8, achieving efficient optical signal transmission. This quantum chip not only leverages the advantages of optical fiber and optical waveguide transmission but also utilizes the high-speed response and precise modulation capabilities of the electro-optic modulator 2, giving the quantum chip advantages such as high signal-to-noise ratio and strong signal transmission stability in signal transmission and processing, which is beneficial for improving the performance of quantum information processing.

[0062] In some embodiments of this disclosure, the electro-optic modulator 2 can be a Mach-Zehnder interferometer (MZI), which utilizes the electro-optic effect to modulate the optical signal using an electrical signal. Specifically, the electrical signal passes through an electro-optic material (such as lithium niobate) in the MZI to change the refractive index of the material, thereby changing the phase of the optical signal in the two modulation arms of the MZI. When the two optical signals meet at the output of the MZI, interference occurs due to the phase difference between the two optical signals, thus modulating the information of the electrical signal onto the phase of the optical signal, achieving electro-optic conversion.

[0063] The length L and phase of the electro-optic modulator 2 The following relationship must be satisfied:

[0064] in Here, is the phase difference, r is the electro-optic coefficient, n is the refractive index, λ is the wavelength, V is the equivalent voltage, and d is the distance between the electrodes. In the phase difference... In the case of a wavelength λ of 1550 nm, based on the refractive index n and electro-optic coefficient r (z-tangential) of the lithium niobate crystal, the equivalent voltage V is 22.37 mV. Assuming a gain of 20 dB from low temperature to room temperature and a matching impedance of 50 Ω at low temperature, the distance d between the electrodes is 10 μm. Without considering the overlap between the optical signal and the modulation electric field, the half-wavelength at room temperature can reach 21.5 mm. Considering the size limitations of the electro-optic modulator 2 and its optical structure, the bent modulation arm shown in Figure 6 can be used to reduce the half-wavelength. If an x-tangential lithium niobate crystal is used, the design disclosed herein is more advantageous for reducing the size of the quantum chip. This disclosure can also use low-temperature electronic devices to amplify the electrical signal to reduce the size of the quantum chip. The figures in this disclosure are for reference only and are not limited to specific orders of magnitude.

[0065] The advantages of the Mach-Zehnder interferometer are as follows: 1) Wide bandwidth: The Mach-Zehnder interferometer can modulate a 6.5 GHz microwave signal into a 1.9 × 10^5 GHz optical signal with a wavelength of 1550 nm. This solves the problems of high spectral efficiency, signal distortion, and reduced transmission performance in the microwave band, achieving efficient conversion and transmission between microwave and optical signals. 2) High compatibility at extremely low temperatures: The phase modulation material used in the Mach-Zehnder interferometer can operate stably in extremely low-temperature environments, making it compatible with devices operating in low-temperature environments such as qubit-1, and suitable for fields such as quantum computing. 3) Low heat loss: The Mach-Zehnder interferometer has a compact structure and low heat load, generating very little heat during operation, which will not interfere with devices such as qubit-1. This helps ensure the stability of the quantum chip in low-temperature environments and improves the overall system performance. 4) High reliability and stability: By using special optical fibers and special treatments at the connection points between the input optical fiber 7 and the output optical fiber 8 and the electro-optic modulation layer 21, as well as at the connection points between multiple optical fiber segments in the input optical fiber 7 and the output optical fiber 8, the Mach-Zehnder interferometer has higher reliability and stability at low temperatures. This helps to reduce the complexity of the quantum chip and improve the reliability of the quantum chip during long-term operation.

[0066] In some embodiments of this disclosure, both the output optical fiber 8 and the input optical fiber 7 are capable of transmitting the optical signal at a temperature of 4K. Here, 4K refers to 4 Kelvin, or -269°C. To ensure stable operation of the optical fiber in extremely low-temperature environments and to maintain stable physical and chemical properties at these temperatures, both the input optical fiber 7 and the output optical fiber 8 include a core layer and a cladding layer disposed outside the core layer. The core layer and the cladding layer have similar coefficients of thermal expansion. Since the external temperature of the quantum chip changes rapidly from 4K to room temperature, the similar coefficients of thermal expansion of the core layer and cladding layer can prevent internal stress cracking of the optical fiber caused by rapid temperature changes. Furthermore, the optical fiber passes through multiple temperature zones during the transition from 4K to room temperature. Being small and having a low thermal load, the optical fiber will not cause drastic impacts on the environment surrounding the electro-optic modulator 2. The input optical fiber 7 and the output optical fiber 8 can be made from multiple optical fiber segments through thermal welding. These segments operate stably at their respective corresponding temperature zones, which helps reduce insertion loss and return loss at the connection points between the input optical fiber 7 and the output optical fiber 8 and the electro-optic modulator 2. For example, the input fiber 7 and the output fiber 8 can be either gold-plated fiber or photonic crystal fiber. Gold-plated fiber enhances resistance to extreme low-temperature brittleness, while photonic crystal fiber improves transmission efficiency at extremely low temperatures through a special structure. Alternatively, the input fiber 7 and the output fiber can be single-mode fiber, which is beneficial for improving signal transmission efficiency and signal-to-noise ratio.

[0067] The electro-optic modulation structure 21 includes at least one pair of modulation arms, which can be connected in parallel or cascaded. Each pair of modulation arms is provided with a pair of signal electrodes 216 and ground electrodes 217 with opposite electric field directions. For example, the electro-optic modulation structure 21 includes one pair of modulation arms, and there can be multiple electro-optic modulators 2, which surround the qubit 1 on the base plate 3. The above structure can be used for multi-channel qubits 1, with each channel of qubit 1 connected to a corresponding electro-optic modulator 2. For example, multiple qubits 1 can also correspond to one channel, or multiple pairs of modulation arms can also correspond to one channel of qubit 1. The electro-optic modulator 2 can be configured with a corresponding electro-optic modulation structure 21 according to the channel structure of the qubit 1.

[0068] In some embodiments of this disclosure, as shown in FIG2, the electro-optic modulation structure 21 includes a pair of modulation arms, specifically a first modulation arm 211 and a second modulation arm 212, with a length ratio of 1:1 and a beam splitting ratio of 1:1. The first modulation arm 211 and the second modulation arm 212 are respectively provided with a pair of signal electrodes 216 and a ground electrode 217 with opposite electric field directions. When a voltage is applied to the signal electrode 216, the optical signals transmitted in the first modulation arm 211 and the second modulation arm 212 undergo phase modulation based on the electro-optic effect, generating a phase difference. Since the first modulation arm 211 and the second modulation arm 212 are of equal length and have the same beam splitting, the modulated optical signals interfere when the beam is combined, allowing the output optical signal to be precisely controlled according to voltage changes.

[0069] In some embodiments of this disclosure, another electro-optic modulation structure 21 is also provided, as shown in Figures 3 and 4. The electro-optic modulation structure 21 includes multiple pairs of modulation arms, which can be connected in parallel or in cascade.

[0070] As shown in Figure 3, this disclosure provides a parallel-structured multi-channel signal modulation electro-optic modulator 2, comprising an electro-optic modulation structure 21 with multiple pairs of modulation arms connected in parallel. Each pair of modulation arms is a Mach-Zehnder interferometer (MZI), and each pair of modulation arms corresponds to one channel of a qubit 1. When a voltage is applied to the corresponding electrodes, each modulation arm independently modulates the phase of the optical signal based on the electro-optic effect. The parallel electro-optic modulation structure with multiple pairs of modulation arms is beneficial for improving the processing power and flexibility of the electro-optic modulator 2, and can also ensure the efficient and independent modulation of each channel in the qubit 1. It is suitable for complex quantum computing systems and realizes high-speed, accurate, and parallel processing of modulated optical signals.

[0071] As shown in Figure 4, this disclosure provides a cascaded multi-channel signal modulation electro-optic modulator 2, including a cascaded electro-optic modulation structure 21 of multiple pairs of modulation arms, where each pair of modulation arms is a Mach-Zehnder interferometer (MZI), and the multiple pairs of cascaded modulation arms can correspond to one channel of a qubit 1. By controlling the voltage applied to the electrodes, the phase of the optical signal is modulated step by step. The cascaded electro-optic modulation structure of multiple pairs of modulation arms not only improves the accuracy of electro-optic modulation but also enhances flexibility and scalability. Through the coordinated work of the multi-stage modulation arms, precise transmission and control of the optical signal are ensured.

[0072] In some embodiments of this disclosure, as shown in FIG5, this disclosure provides a quantum chip having multiple electro-optic modulators 2, wherein the electro-optic modulation structure 21 includes a pair of modulation arms, which is a Mach-Zehnder electro-optic modulation structure, and multiple electro-optic modulators 2 are arranged around a quantum bit 1 on a substrate 3. The multiple electro-optic modulators 2 surrounding the quantum bit 1 enable the electrical signal of each channel in the quantum bit 1 to control the corresponding electro-optic modulator 2, thereby modulating the optical signal transmitted in each electro-optic modulator 2. This distributed structure of multiple electro-optic modulators is suitable for multi-channel quantum bits 1, improving the flexibility of the system.

[0073] In some embodiments of this disclosure, another electro-optic modulation structure 21 is also provided, as shown in FIG6. This electro-optic modulation structure 21 includes a pair of bent modulation arms, namely, a first modulation arm 211 and a second modulation arm 212 bent and disposed in the electro-optic modulator 2. Bending the modulation arms in the electro-optic modulator 2 is beneficial to reducing the size and area occupied by the quantum chip.

[0074] In some embodiments of this disclosure, as shown in FIG7, an electro-optic modulator 2 is provided, including a substrate 213, an optical waveguide layer 214, an electro-optic modulation layer 215, a signal electrode 216, and a ground electrode 217. The optical waveguide layer 214 is disposed on the substrate 213, the electro-optic modulation layer 215 is disposed on the optical waveguide layer 214, and the signal electrode 216 and the ground electrode 217 are disposed on the electro-optic modulation layer 215. For example, the substrate 213 is made of silicon, the optical waveguide layer 214 is made of silicon dioxide, and the electro-optic modulation layer 215 is made of at least one of lithium niobate, gallium arsenide, and lithium tantalate. As another example, the electro-optic modulator 2 further includes a protective layer disposed on the electro-optic modulation layer 215, configured to protect the electro-optic modulation layer 215.

[0075] In the electro-optic modulator 2, substrate 213 serves as the base, providing stable physical support and good thermal conductivity, which helps maintain the overall stability and heat dissipation of the electro-optic modulator 2. Optical waveguide layer 214 is configured to guide the optical signal through a specific path, reducing optical signal loss. Electro-optic modulation layer 215, as the core of the modulated optical signal, is disposed on top of optical waveguide layer 214. It dynamically modulates the optical signal by applying an electrical signal to signal electrode 216, achieving rapid and precise modulation of the optical signal. The quantum chip operates at extremely low temperatures; lithium niobate or lithium tantalate crystals ensure the electro-optic modulation effect, preventing signal attenuation and ensuring normal operation of the electro-optic modulator 2 at extremely low temperatures. A protective layer protects the electro-optic modulation layer 215 from damage by the external environment, improving the stability and reliability of the electro-optic modulator 2. Substrate 213, optical waveguide layer 214, and electro-optic modulation layer 215 work together to ensure stable operation of the electro-optic modulator 2 at extremely low temperatures.

[0076] In some embodiments of this disclosure, the coupling methods between the electro-optic modulation layer 215 and the input optical fiber 7, and / or between the electro-optic modulation layer 215 and the output optical fiber 8, include any one of end-face coupling, fiber skewing, micromirror, focusing grating coupling, lens fiber, chip flip-chip, and photonic interposer. For example, the coupling method can be V-groove end-face coupling, wherein the V-groove is configured to accommodate the input optical fiber 7 and the output optical fiber 8, thereby achieving coupling between the input optical fiber 7 and / or the output optical fiber 8 and the electro-optic modulation layer 215. Furthermore, a wedge structure can be provided at the front end of the V-groove to enhance signal transmission and reduce loss at the coupling point.

[0077] End-face coupling refers to directly aligning and bringing the end face of the input fiber 7 close to the input end of the electro-optic modulation layer 215, or directly aligning and bringing the end face of the output fiber 8 close to the output end of the electro-optic modulation layer 215, to achieve coupled transmission of optical signals. End-face coupling ensures the transmission of optical signals from the input fiber 7 to the electro-optic modulation layer 215, and from the electro-optic modulation layer 215 to the output fiber 8, facilitating high-precision alignment and reducing optical signal loss. In some embodiments of this disclosure, the use of V-groove end-face coupling combined with a wedge structure at the front end not only precisely fixes the optical fibers and improves the stability of the coupling between the input fiber 7 and the output fiber 8 and the electro-optic modulation layer 215, but also uses the wedge structure to converge and guide the optical signals, significantly enhancing signal transmission efficiency, reducing loss at the coupling point, and thus improving the overall performance of the electro-optic modulator 2.

[0078] In some embodiments of this disclosure, fiber optic beveling further improves coupling efficiency by optimizing the angle of the fiber end face; micromirrors utilize the principle of reflection to flexibly adjust the optical path; and flip-chip design is suitable for highly integrated application scenarios and helps reduce packaging complexity.

[0079] In some embodiments of this disclosure, mode conversion structures are provided between the input optical fiber 7 and the output optical fiber 8 and the electro-optic modulation layer 215, respectively, configured to match the propagation modes of the input optical fiber 7 and the output optical fiber 8 with the electro-optic modulation layer 215.

[0080] The mode-spot conversion structure refers to a specific structure set between the electro-optic modulation layer 215 and the input optical fiber 7 and the output optical fiber 8, which is used to match the propagation modes between the optical fiber and the electro-optic modulation layer 215. Since the optical fiber and the electro-optic modulation layer 215 have different mode field diameters and optical field distributions, direct coupling will lead to energy loss. The mode-spot conversion structure reduces energy loss by changing the distribution and size of the optical field, enabling a smooth transition of the optical signal as it propagates from the optical fiber to the electro-optic modulation layer 215.

[0081] In some embodiments of this disclosure, the mode conversion structure can be a conical or radial mode conversion structure, as shown in Figure 8. Using a conical or radial mode conversion structure allows for more effective mode field matching and improves coupling efficiency. The mode conversion structure can adjust the distribution of the optical field, enabling the optical signal to adapt to the mode field characteristics of the electro-optic modulation layer 215 during propagation, thereby reducing energy loss due to mode mismatch. Therefore, the mode conversion structure can improve the performance of the electro-optic modulator 2, ensuring efficient transmission and modulation of the optical signal.

[0082] The working principle of the quantum chip disclosed herein is as follows: A quantum bit 1 is installed within the quantum chip. An optical signal is input to an electro-optic modulator 2 via an optical fiber. The optical signal is modulated by the electrical signal generated by the quantum bit 1 within the electro-optic modulator 2 and then output. Specifically, the optical signal enters a beam splitter 22 via an input optical fiber 7. Under the action of the beam splitter 22, it is split into two beams. To enhance the phase amplitude change caused within a unit length, the two beams are modulated in opposite directions by the electrical signal generated from the quantum bit 1, as shown in Figure 2. The electric fields in the two modulation arms are in opposite directions. The modulated two beams interfere through a beam combiner 23, and then the modulated optical signal from the beam combiner 23 is output via an output optical fiber 8. Finally, after the optical signal is transmitted to room temperature, it is demodulated by a demodulation module.

[0083] The detailed descriptions listed above are merely specific descriptions of feasible implementations of this disclosure and are not intended to limit the scope of protection of this disclosure. All equivalent implementations or modifications made without departing from the spirit of the art of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A quantum chip, characterized in that, include: Quantum bits are configured to generate electrical signals; An electro-optic modulator, electrically connected to the qubit, configured to modulate an optical signal transmitted in the electro-optic modulator based on an electrical signal input to the qubit, so that the optical signal carries qubit information generated by the qubit.

2. The quantum chip according to claim 1, characterized in that, It also includes a base plate, on which a first region, a second region, and a first pad are provided. The first pad is disposed at the edge of the base plate and surrounds the first region and the second region. The first region is configured to fix the quantum bit, the second region is configured to fix the electro-optic modulator, and the first pad is configured to electrically connect the quantum bit and the microwave cable.

3. The quantum chip according to claim 1, characterized in that, The electro-optic modulator is further provided with a ceramic shell, which is configured to cover and seal the electro-optic modulator to avoid interference of the electro-optic modulator with the quantum bit.

4. The quantum chip according to claim 2, characterized in that, The electro-optic modulator includes: An input optical fiber is configured to input the optical signal. A beam splitter, which is connected to the input optical fiber, is configured to split the optical signal into beams; An electro-optic modulation structure, connected to the beam splitter, is configured to modulate the phase of an optical signal from the beam splitter; A beam combiner, which is connected to the electro-optic modulation structure, interferes with the optical signal from the electro-optic modulation structure; An output optical fiber is connected to the combiner and outputs an optical signal from the combiner.

5. The quantum chip according to claim 4, characterized in that, The electro-optic modulation structure includes at least one pair of modulation arms, which can be connected in parallel or cascaded.

6. The quantum chip according to claim 4, characterized in that, There are multiple electro-optic modulators, and the multiple electro-optic modulators surround the quantum bit on the base plate.

7. The quantum chip according to claim 4 or 5, characterized in that, Each pair of modulation arms is provided with a pair of signal electrodes and a ground electrode with opposite electric field directions.

8. The quantum chip according to claim 4, characterized in that, The electro-optic modulator includes: Substrate; An optical waveguide layer is disposed on a substrate; An electro-optic modulation layer is disposed on the optical waveguide layer.

9. The quantum chip according to claim 8, characterized in that, The coupling method between the electro-optic modulation layer and the input optical fiber and / or the coupling method between the electro-optic modulation layer and the output optical fiber includes any one of end-face coupling, fiber beveling, micromirror, focusing grating coupling, lens fiber, chip flip-chip, and photonic interposer.

10. The quantum chip according to claim 4, characterized in that, The output optical fiber and the input optical fiber are capable of transmitting the optical signal at a temperature of 4K.

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