Quantum bit reading process including coherent shelving

Abstract

To provide a method of, a system for, an apparatus for, a computer program product for, and / or an equivalent for executing quantum state determination for atom object trapped in an atom object confinement device.SOLUTION: The present invention is directed to a method of reading an atom object and / or a quantum state of a quantum bit by using coherent shelving. A controller makes a first beam with a first wavelength and a second beam with a second wavelength incident on the quantum bit and makes a read beam incident on the quantum bit. The first wavelength and the second wavelength allow quantum bits to be combined in their stable states in a quantum space. In the stable state, the quantum bit has longer life as compared with time necessary for execution of a reading operation. The first beam and the second beam are generated by a manipulation source 60 operated by a manipulation source driver controlled by the controller.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims the benefit of priority of U.S. Application No. 63 / 200263, filed on Feb. 25, 2021, the entire content of which is incorporated herein by reference.

[0002] Various embodiments relate to apparatuses, systems, and methods for determining the quantum state of an atomic object trapped in an atomic object containment apparatus. For example, some exemplary embodiments relate to readout procedures for using ion shelving to read the state of qubits in a trapped atomic object quantum computer.

Background Art

[0003] Ion traps can use a combination of electric and magnetic fields to capture multiple atomic objects within a potential well. Atomic objects can be trapped for many purposes, including, for example, mass spectrometry, research, and / or control of quantum states. In various scenarios, it can be important to rapidly and with a high level of accuracy determine the quantum state of an atomic object. For example, a trapped atomic object can be used as a qubit in a trapped atomic object quantum computer. The qubit space used for the two states of a qubit can have similar energy levels. This can cause off - resonant errors to be introduced into the quantum state determination. Through noted efforts, ingenuity, and innovation, many deficiencies of previous atomic object quantum state determination techniques have been solved by developing solutions structured in accordance with embodiments of the present invention, many examples of which are detailed herein.

Summary of the Invention

[0004] Exemplary embodiments provide methods, systems, apparatus, computer program products, and / or similar for performing quantum state determination of atomic objects trapped within an atomic object confinement device. For example, various embodiments provide methods, systems, apparatus, computer program products, and / or similar for qubit readout operations that do not include and / or provide technical solutions to the technical problem of non-resonant errors in qubit readout. For example, various embodiments provide methods, systems, apparatus, computer program products, and / or similar that reduce non-resonant errors (with respect to conventional qubit readout processes). For example, in a trapped atomic object quantum computer, atomic objects trapped within an atomic object confinement device can be used as qubits of the quantum computer. Two quantum states of the hyperfine structure of an atomic object can be used as a qubit space in which one of the two quantum states is referred to as up or 1 and the other of the two quantum states is referred to as down or 0. The two quantum states of the hyperfine structure used as a qubit space may have similar energy levels. For example, two quantum states in a qubit space can be separated by less than 50 gigahertz (GHz) (e.g., less than 13 GHz). [Means for solving the problem]

[0005] Conventional readout procedures involve applying a laser beam, which couples only one of the qubit states, to the atomic object to be readout. As used herein, the term readout procedure refers to the process used to determine the quantum state of an atomic object. When the quantum state of an atomic object collapses to a coupled state in qubit space during the measurement process, the laser excites it, resulting in the emission of photons as the atomic object decays from the excited state. After decay, the atomic object can be continuously excited by the laser and repeatedly emit photons. These photons can be focused using various photodetectors. When the quantum state of the atom collapses to the other (uncoupled) qubit state, the atomic object does not interact with the laser and no photons are emitted. However, the closer the two quantum states in qubit space are in terms of energy, the more likely it is that the qubit with the quantum state that collapses to an uncoupled qubit state will interact with the laser, resulting in a non-resonant error.

[0006] Various embodiments provide readout procedures that include a coherent shelving approach to reduce and / or prevent non-resonant errors. In particular, a first beam of a first wavelength and a second beam of a second wavelength may be applied to the atomic object to be readout. The first and second beams are configured to couple a first state in qubit space to a stable state outside of qubit space. For example, if the quantum state of the atomic object collapses to a first state in qubit space, the quantum state of the atomic object evolves to a stable state outside of qubit space. In various embodiments, the atomic object evolves coherently to a stable state. For example, the atomic object is “shelved” for the readout procedure by evolving the quantum state of the atomic object to a stable state. If the quantum state of the atomic object collapses to a second state in qubit space, the quantum state of the atomic object remains in the second state, unaffected by the first and second beams. The readout beam can then be applied to the atomic object. If the quantum state of an atomic object collapses to a second state, the readout beam interacts with the atomic object and causes it to emit a photon. This photon can be detected by a photon detector. If the quantum state of an atomic object collapses to a first state and then develops into a stable state, the readout beam does not interact with the atomic object, and no photon is emitted. Furthermore, the stable state has an energy level that is not similar to any state in the qubit space. For example, the stable state can be separated from both levels in the qubit space by at least 100 GHz (e.g., at least 1 terahertz (THz)). The energy difference between the second state and the stable state in the qubit space is large enough so that the readout operation is not affected by non-resonant errors.

[0007] According to one aspect of the present disclosure, a method for reading a qubit from a trapped ion quantum computer is provided, including a coherent shelving procedure. In an exemplary embodiment, the method includes causing a controller of the trapped ion quantum computer to cause a first beam of a first wavelength and a second beam of a second wavelength to be incident on the qubit. The first and second wavelengths are configured to couple the quantum space state of the qubit to a stable state. The stable state has a lifetime longer than the length of time required to perform the readout operation. The method further includes causing the controller to cause the readout operation to be performed on the qubit.

[0008] In one exemplary embodiment, the qubit is a monovalent ionized ytterbium atom, with a first wavelength of 411 nm and a second wavelength of 3.4 micrometers, and the stable state is in the F manifold.

[0009] In one exemplary embodiment, the method further includes receiving a signal from a photodetector by a controller, and determining the quantum state of a qubit based on the signal by the controller.

[0010] In one exemplary embodiment, causing a readout operation to be performed includes causing a readout beam to be incident on a qubit and monitoring a signal generated by a photodetector to determine whether the qubit fluoresces in response to the readout beam being incident on it.

[0011] In one exemplary embodiment, the method further includes reinitializing the qubit.

[0012] In one exemplary embodiment, reinitializing a qubit involves causing a third beam of a third wavelength and a fourth beam of a second wavelength to be incident on the qubit.

[0013] In one exemplary embodiment, the third and fourth beams are incident on the qubit in a manner that overlaps at least partially in time.

[0014] In one exemplary embodiment, the qubit is a monovalent ionized ytterbium atom, with a second wavelength of 3.4 micrometers and a third wavelength of 976 nm.

[0015] In one exemplary embodiment, the third and fourth beams are incident on the qubit for a period of less than 30 milliseconds.

[0016] In one exemplary embodiment, the method further includes determining that a qubit should be read out while executing a quantum circuit, and that a first beam and a second beam are incident on the qubit in response to the determination that the qubit should be read out. In one exemplary embodiment, the method further includes reinitializing the qubit and then continuing to execute the quantum circuit using that qubit.

[0017] Another aspect of the present disclosure provides a controller for a trapped-ion quantum computer. In one exemplary embodiment, the controller comprises at least one processing device, the processing device communicating with at least one manipulation source driver. The processing device is configured to cause the controller to inject a first beam of a first wavelength and a second beam of a second wavelength into a qubit, and to inject a readout beam into the qubit. The first and second wavelengths are configured to couple the quantum space state of the qubit into a stable state. The stable state has a lifetime longer than the length of time required to perform the readout operation. The first and second beams are generated by at least one manipulation source operated by at least one manipulation source driver.

[0018] In an exemplary embodiment, the qubit is a singly-ionized ytterbium atom, the first wavelength is 411 nm, the second wavelength is 3.4 micrometers, and the ground state is in the F manifold.

[0019] In an exemplary embodiment, the processing device communicates with a photodetector, and the processing device is further configured such that a controller receives a signal from the photodetector, the signal responds to the result of a read beam incident on the qubit, and based on the signal, the state of the qubit is determined.

[0020] In an exemplary embodiment, to perform a read operation, the processing device is configured to cause a read beam to be incident on the qubit and monitor a signal generated by the photodetector to determine whether the qubit fluoresces in response to the read beam being incident on the qubit.

[0021] In an exemplary embodiment, the processing device is further configured to cause the controller to re-initialize the qubit.

[0022] In an exemplary embodiment, re-initializing the qubit includes causing a third beam of a third wavelength and a fourth beam of a second wavelength to be incident on the qubit.

[0023] In an exemplary embodiment, the third beam and the fourth beam are incident on the qubit such that they at least partially overlap in time.

[0024] In an exemplary embodiment, the qubit is a singly-ionized ytterbium atom, the second wavelength is 3.4 micrometers, and the third wavelength is 976 nm.

[0025] In an exemplary embodiment, the third and fourth beams are incident on the qubit over a period of less than 30 milliseconds.

[0026] In an exemplary embodiment, the processing device is further configured to determine that a qubit should be read while executing a quantum circuit, and the first beam and the second beam are incident on the qubit in response to determining that the qubit should be read.

[0027] In an exemplary embodiment, after re-initializing a qubit, the processing device is further configured to continue executing the quantum circuit using that qubit.

[0028] The present invention has been described in general terms and reference is made to the accompanying drawings, which are not necessarily to scale.

Brief Description of the Drawings

[0029] [Figure 1] FIG. is a schematic diagram showing an exemplary quantum computing system including an atomic object confinement device that can be used to execute a readout procedure of an exemplary embodiment. [Figure 2] FIG. is a schematic diagram of some of the energy levels of an exemplary atomic object that can be used when executing a coherent shelving procedure of an exemplary embodiment. [Figure 3] FIG. is a flowchart illustrating various processes, operations, and / or procedures of a readout procedure including shelving according to an exemplary embodiment. [Figure 4] FIG. is a schematic diagram of some of the energy levels of an exemplary atomic object that can be used to execute an unshelving procedure after executing a readout procedure including shelving according to an exemplary embodiment. [Figure 5] FIG. is a schematic diagram of an exemplary controller of a quantum computer configured to execute one or more deterministic reshaping and / or reordering functions according to various embodiments. [Figure 6]This is a schematic diagram of an exemplary computing entity of a quantum computer system that may be used in one exemplary embodiment. [Modes for carrying out the invention]

[0030] Next, the present invention will be described in more detail below with reference to the accompanying drawings, which illustrate some, but not all, embodiments of the present invention. In fact, the present invention may be embodied in many different forms and should not be construed as being limited to the embodiments described herein, but rather these embodiments are provided to satisfy the legal requirements to which this disclosure is applicable. The phrase "or" (also written as " / ") is used herein in both an alternative and a conjunctive sense unless otherwise noted. The phrases "exemplary" and "exemplary" are used as examples that do not indicate a level of quality. The phrases "generally," "substantially," and "about" refer, unless otherwise noted, to the range of engineering and / or manufacturing tolerances and / or the range of user measurement capabilities. Throughout, similar numbers refer to similar elements.

[0031] In various embodiments, methods, apparatus, systems, computer program products, and / or similar are provided for performing a readout procedure including coherent shelving. In various embodiments, the readout procedure is used to determine the quantum state of an atomic object. In various embodiments, the atomic object is an ion or an atom. In one exemplary embodiment, the atomic object is monovalent ionized ytterbium. In one exemplary embodiment, the atomic object is trapped in an atomic object confinement device such as an ion trap. In various embodiments, the atomic object is used as a qubit in a trapped atomic object quantum computer. For example, the readout procedure may be used to determine whether the wave function of the atomic object collapses and, as a result of the wave function collapse, the qubit is in a first state or a second state in a two-state qubit space defined for the qubit.

[0032] In various embodiments, the readout procedure includes performing a shelving procedure, reading out a qubit, and optionally performing an unshelving procedure. The shelving procedure includes causing a first beam of a first wavelength and a second beam of a second wavelength to be incident on the atomic object to be read. The first and second beams are configured to couple a first state in qubit space to a stable state outside of qubit space. The stable state has a lifetime longer than the time required to read out the qubit. For example, when the quantum state of the atomic object collapses to a first state in qubit space, the quantum state of the atomic object evolves to a stable state outside of qubit space by the application of the first and second beams to the qubit to be read. In various embodiments, the atomic object evolves coherently to the stable state. Coherently evolving the atomic object from the first state to the evolved stable state is ultimately equivalent to applying a unitary transformation to the system via the application of the first and second beams to the qubit to be read. This is in contrast to the non-coherent evolution of quantum states, which is ultimately a non-unitary transformation of the system. In addition, the coherent evolution of an atomic object to a stable state does not have the time constraints of the conventional non-coherent evolution of quantum states due to shelving during the read operation. In other words, the atomic object is coherently shelved for the performance of the read operation. Also, because the atomic object is coherently shelved, the quantum information stored by the atomic object is not disturbed. In contrast, as a result of non-coherent shelving of an atomic object, the quantum information stored by the non-coherently shelved atomic object is destroyed.

[0033] When the quantum state of an atomic object collapses to a second state in qubit space, the quantum state of the atomic object remains in the second state, unaffected by the first and second beams. A readout beam can then be applied to the atomic object. If the quantum state of the atomic object collapses to the second state, the readout beam interacts with the atomic object, causing it to emit a photon. This photon can be detected by a photon detector. If the quantum state of the atomic object collapses to the first state and then evolves into a stable state, the readout beam does not interact with the atomic object, and no photon is emitted. Furthermore, the stable state has an energy level that is not similar to any state in qubit space. For example, the stable state can be separated from both levels in qubit space by at least 100 GHz (e.g., at least 1 terahertz (THz)). The energy difference between the second state in qubit space and the stable state is large enough so that the readout operation is not affected by non-resonant errors.

[0034] Exemplary quantum computing system with atomic object confinement device Figure 1 is a schematic diagram of an exemplary quantum computing system 100, which includes an atomic object confinement device 300 (e.g., an ion trap and / or similar) according to an exemplary embodiment. In various embodiments, the quantum computing system 100 comprises a computing entity 10 and a quantum computer 110. In various embodiments, the quantum computer 110 comprises a controller 30, a cryostat and / or vacuum chamber 40 surrounding the confinement device 300 (e.g., an ion trap), and one or more manipulation sources 60. For example, the cryostat and / or vacuum chamber 40 may be a pressure-controlled chamber. In an exemplary embodiment, one or more manipulation sources 60 may comprise one or more lasers (e.g., optical lasers, microwave sources, and / or similar). In various embodiments, one or more manipulation sources 60 are configured to manipulate one or more atomic objects in the confinement device and / or cause the development of their controlled quantum states. For example, the manipulation source 60 may be configured to generate a first beam at a first wavelength λ1, a second beam at a second wavelength λ2, a third beam at a third wavelength λ3, a fourth beam at a second wavelength λ2, a readout beam at a readout wavelength, and / or similar. For example, in one exemplary embodiment, if one or more manipulation sources 60 comprise one or more lasers, the lasers may irradiate an atomic object trapped in a cryostat and / or confinement device 300 within a vacuum chamber 40 with one or more laser beams. In various embodiments, the first beam, second beam, third beam, fourth beam, and / or readout beam may be continuous laser beams or pulsed laser beams.

[0035] In various embodiments, the first wavelength λ1 is substantially equal to 411 nm. In various embodiments, the first beam is generated by a first manipulation source 60 configured to produce a 411 nm beam with very good frequency stability. For example, in one exemplary embodiment, the first beam is generated by the first manipulation source 60 to have a frequency of 729 THz with frequency stability of less than 100 kHz. In other words, the first manipulation source 60 is configured to produce a first beam of 729 THz within 100 kHz.

[0036] In various embodiments, the second wavelength λ2 is substantially equal to 3.4 μm. In various embodiments, the second beam is generated by a second manipulation source 60 configured to produce a 3.4 μm beam with very good frequency stability. For example, in one exemplary embodiment, the second beam is generated by the second manipulation source 60 to have a frequency of 88.2 THz with frequency stability below 100 kHz. In other words, the second manipulation source 60 is configured to produce a second beam within 100 kHz at 88.2 THz. In one exemplary embodiment, the manipulation source configured to produce the second beam comprises a periodically polarized reversal lithium niobate (PPLN) waveguide. In one exemplary embodiment, the manipulation source 60 configured to produce the second beam comprises a tunable Ti:S laser and a 1550 nm laser. In an exemplary embodiment, the manipulation source 60 configured to generate a second beam comprises a 1064 nm light source and / or laser, as well as a tunable laser having an intrinsic wavelength substantially equal to 1550 nm.

[0037] In various embodiments, the quantum computer 110 includes an optical focusing system configured to focus and / or detect photons generated by qubits (for example, in a readout procedure). The optical focusing system may comprise one or more optical elements (e.g., lenses, mirrors, waveguides, optical fiber cables, and / or similar) and one or more photodetectors. In various embodiments, the photodetectors may be photodiodes, photomultiplier tubes, charge-coupled device (CCD) sensors, complementary metal-acid film-semiconductor (CMOS) sensors, micro-electromechanical system (MEMS) sensors, and / or other photodetectors that are sensitive to light of the expected fluorescence wavelength of the quantum computer's qubits. In various embodiments, the detectors may communicate electronically with the controller 30 via one or more A / D converters 525 (see Figure 5) and / or similar.

[0038] In various embodiments, the quantum computer 110 comprises one or more voltage sources 50. For example, the voltage source 50 may comprise a plurality of voltage drivers and / or voltage sources and / or at least one RF driver and / or voltage source. In one exemplary embodiment, the voltage source 50 may be electrically coupled to a corresponding potential generating element (e.g., an electrode) of the confinement device 300.

[0039] In various embodiments, the computing entity 10 is configured to allow a user to provide input to the quantum computer 110 (for example, through the user interface of the computing entity 10), receive and display outputs from the quantum computer 110, and / or perform similar operations on them. The computing entity 10 may communicate with the controller 30 of the quantum computer 110 via one or more wired or wireless networks 20 and / or via direct wired and / or wireless communication. In exemplary embodiments, the computing entity 10 may translate, configure, format, and / or perform similar operations on information / data, quantum computing algorithms and / or circuits, and / or the like into a computing language, executable instructions, command set, and / or the like that the controller 30 can understand and / or implement.

[0040] In various embodiments, the controller 30 is configured to control a voltage source 50, a cryostat system and / or vacuum system that controls the temperature and pressure within the cryostat and / or vacuum chamber 40, a manipulation source 60, and / or other systems configured to control various environmental conditions (e.g., temperature, pressure, and / or similar) within the cryostat and / or vacuum chamber 40, and / or to manipulate one or more atomic objects within the confinement device and to cause a controlled evolution of the quantum state of the atomic objects. For example, the controller 30 may cause a controlled evolution of the quantum state of one or more atomic objects within the confinement device to execute a quantum circuit and / or algorithm. For example, the controller 30 may cause a readout procedure, including coherent shelving, to be performed, possibly as part of executing a quantum circuit and / or algorithm. In various embodiments, the atomic objects confined within the confinement device are used as qubits in a quantum computer 110.

[0041] Exemplary shelving procedure Figure 2 illustrates a portion of the energy level diagram 200 for an exemplary atomic object that can be used as a qubit in a quantum computing system in one exemplary embodiment. In particular, an atomic object acting as a qubit in a quantum computing system starts in one of two states in the qubit space 210. For example, the qubit space 210 may be the ground state (e.g., S) of the atomic object, which in various embodiments may be referred to as the zero or off state (e.g., |0>) or the down state (e.g., |↓>). 1 / 2The manifold may include a first qubit state 212 of the ultrafine state l=0, m=0. The qubit space 210 may further include a second qubit state 214 of the ultrafine state l=1, m=0 of the ground state of the atomic object, which in various embodiments may be referred to as 1 or the on state (e.g., |1) or the up state (e.g., |↑>). In various embodiments, the atomic object is an ion or an atom. For example, the atomic object may be monovalent ionized ytterbium. The atomic object used as a qubit in a quantum system is also simply referred to as a qubit.

[0042] In various embodiments, two states in the qubit space 210 can be separated by a relatively small energy difference corresponding to the qubit state separation wavelength λ0. For example, in one exemplary embodiment, two qubit states in the qubit space 210 are separated by an energy difference corresponding to a frequency difference of less than 20 GHz (e.g., less than 15 GHz or less than 13 GHz). In other words, the two states in the qubit space 210 are separated by an energy difference corresponding to a qubit separation wavelength λ0 of at least 1.5 cm (e.g., at least 2.0 cm or at least 2.3 cm), resulting in an energy difference of 8.3 × 10⁻¹⁰. -5 Less than eV (for example, 6.2 × 10⁻¹⁰) -5 Less than eV or 5.4 × 10⁻⁶ -5 Separation occurs at (below eV)

[0043] In various embodiments, the shelving procedure includes applying two beams such that two beams are incident on a qubit. As used herein, the phrase “applying beams” includes providing beams and / or causing beams to be incident on an atomic object and / or a qubit. The two beams include a first beam with a first wavelength λ1 and a second beam with a second wavelength λ2. In various embodiments, the first and second beams may be applied simultaneously and / or at the same time, for overlapping time and / or alternating time. In one exemplary embodiment, the first beam is applied, and then, after the first beam has completed its incidence on the atomic object, the second beam is applied.

[0044] In one exemplary embodiment, the first and second beams may be applied in a phase-coherent manner. For example, the first and second beams may be applied in the same phase in an embodiment in which the first and second beams are applied simultaneously and / or overlappingly. For example, the first and second beams may be applied in a continuous phase in an embodiment in which the first and second beams are applied to the atomic object in an alternating manner or in which the first beam is applied first, followed by the second beam. For example, when the first and second beams are applied alternately, the phase of the first beam when the application of the first beam is stopped may be the phase of the second beam when the application of the second beam begins (for example, with a slight modification that may take into account any phase change in the time delay between when the application of the first beam is stopped and when the application of the second beam begins). In various embodiments, the first and second beams may not be applied in a coherent manner. For example, the first and second beams may be applied by a specific phase offset, an evolving phase offset, and / or similar.

[0045] In one exemplary embodiment, the first and second beams may be applied at a specific angle between their propagation directions. For example, depending on the application, the first and second beams may propagate in the same direction (e.g., substantially parallel propagation directions), in opposite directions (e.g., substantially antiparallel propagation directions), in orthogonal directions (e.g., substantially perpendicular propagation directions), or at any other angle between their propagation directions. In one exemplary embodiment, the first and second beams may be applied with a specific polarization offset. For example, depending on the application, the first and second beams may be applied with the same polarization, opposite polarization (e.g., the first beam may be right-linearly polarized and the second beam left-linearly polarized, or vice versa; the first beam may be right-circularly polarized and the second beam left-circularly polarized), and / or similar polarization.

[0046] As noted above, the first beam has a first wavelength λ1 and the second beam has a second wavelength λ2. In one exemplary embodiment, the first wavelength λ1 is substantially equal to 411 nm and the second wavelength λ2 is substantially equal to 3.4 μm. In various embodiments, the first wavelength λ1 couples a first state (e.g., ON state 214) in the qubit space 210 to one or more states in the intermediate manifold 220. In the illustrated embodiment, the intermediate manifold 220 is D 5 / 2 The F=3 manifold. In various embodiments, a second wavelength λ2 couples one or more states of the intermediate manifold 220 to one or more stable states of the shelving manifold 230. In various embodiments, coupling a first state of the qubit space 210 to one or more states of the intermediate manifold 220, and one or more states of the intermediate manifold to one or more stable states of the shelving manifold 230 is coherent. In the embodiments illustrated, the shelving manifolds are F=3 and F=4, F 7 / 2The shelving manifold is included. One or more stable states of the shelving manifold 230 each have a lifetime longer than the time required to read out a qubit. As is understood, one or more stable states of the shelving manifold 230 are outside the qubit space 210. Furthermore, one or more stable states of the shelving manifold 230 each have an energy level that is not similar to any state in the qubit space 210. For example, a stable state can be isolated from both levels in the qubit space by an energy difference corresponding to a frequency of at least 100 GHz (e.g., at least 1 terahertz (THz)). The energy difference between the second state in the qubit space and the stable state is large enough so that the readout operation is not affected and / or limited by non-resonant errors.

[0047] Therefore, when a qubit is in a first state in qubit space 210 (e.g., the ON state 214), applying the first and second beams to the qubit causes the qubit to transition from the first state in qubit space 210 to a stable state in the shelving manifold 230 via the intermediate manifold 220. When a qubit is in a second state in qubit space 210 (e.g., the OFF state 212), applying the first and second beams to the qubit has no effect on the qubit. For example, the second state in qubit space 210 is not coupled to the intermediate manifold 220 via the first wavelength λ1, and / or is only very weakly coupled. A readout beam may be applied to a qubit to check whether the qubit fluoresces. For example, a qubit fluoresces if it was in a second state in qubit space, and does not fluoresce if it was originally in a first state in qubit space and is now shelved to a stable state outside of qubit space.

[0048] Figure 3 is a flowchart illustrating various processes, operations, and / or procedures for executing at least a portion of a quantum algorithm and / or circuit, including a readout procedure that includes shelving, according to an exemplary embodiment. In various embodiments, the processes, operations, and / or procedures shown in Figure 3 are executed by the controller 30 of the quantum computing system 100.

[0049] Beginning in step / operation 302, the controller 30 causes the quantum computer 110 to execute at least a portion of the quantum algorithm and / or circuit. For example, the controller 30 may include means such as a processing device 505, memory 510, driver controller element 515, A / D converter 525, and / or similar (see Figure 5) for executing at least a portion of the quantum algorithm and / or circuit. For example, the controller 30 may receive the quantum algorithm and / or circuit provided by, for example, the computing entity 10. The controller 30 may then queue a number of commands and execute the queue of commands to cause at least a portion of the quantum algorithm and / or circuit to be executed. For example, executing at least part of a quantum algorithm and / or circuit may include initializing one or more qubits (e.g., placing one or more atomic objects into the qubit space 210), transporting at least some of the one or more qubits to one or more specific arrangements within the atomic object confinement device 300, executing one or more, one and / or two, and / or multi-qubit gates on at least some of the one or more qubits, and / or similar operations.

[0050] In step / operation 304, while the quantum computer 110 executes at least part of the quantum algorithm and / or circuitry, the controller 30 determines that a qubit should be read out. Reading out a qubit generally involves applying a readout beam to the qubit to cause the qubit's quantum state to collapse into one of the states in the qubit space 210, and determining which state in the qubit space 210 the qubit's quantum state has collapsed into, based on whether the qubit fluoresces. For example, the controller 30 may determine that a set of upcoming and / or next commands to be executed corresponds to reading out a qubit. For example, the controller 30 may include means such as a processing device 505, memory 510, and / or similar for determining that a set of upcoming and / or next commands to be executed corresponds to reading out a qubit.

[0051] In response to the determination that a qubit is to be read out (and possibly transporting the qubit to be read out to its appropriate location within the atomic object confinement device 300), the controller 30 may, in step / operation 306, cause a coherent shelving procedure to be performed on the qubit. For example, the controller 30 may cause a first manipulation source 60 to generate a first beam of a first wavelength λ1 and apply the first beam to the qubit to be read out. The controller 30 may cause a second manipulation source 60 to generate a second beam of a second wavelength λ2 and apply the second beam to the qubit to be read out. As described above, in various embodiments, the first and second beams may be applied simultaneously, in an overlapping manner, in an alternating manner, and / or similar manner. In an exemplary embodiment, the first beam is applied, and then the second beam is applied after the application of the first beam has been stopped. For example, the controller 30 may include means such as a processing device 505, a memory 510, a driver controller element 515, and / or similar, for causing a first manipulation source to apply a first beam and a second manipulation source to apply a second beam. As described above, the first and second beams may be applied by a specific phase relationship, a specific relationship between the propagation directions of the first and second beams, and / or a specific relationship between the polarizations of the first and second beams. In one exemplary embodiment, the first and second beams may be applied over a time of 10 to 50 μs (e.g., 10 to 30 μs, 20 to 40 μs, and / or similar times).

[0052] In step / operation 308, the controller 30 causes the readout manipulation source 60 to apply the readout beam to the qubit to be readout. As noted above, if the qubit was shelved in step 306 (for example, the qubit was in the first state of qubit space 210 and therefore coherently transitioned to a stable state in the shelving manifold 230), the qubit will not emit fluorescence in response to the readout beam being applied to it. If the qubit was not shelved in step 306 (for example, the qubit was previously in the second state of qubit space 210 and is now in the second state and therefore has not transitioned to a stable state in the shelving manifold 230), the qubit will emit fluorescence in response to the readout beam being applied to it. The controller 30 then receives a signal from the optical focusing system of the quantum computer 110 indicating whether fluorescence was detected / observed or not. Based on the received signal, the controller 30 determines which state in the qubit space 210 the quantum state of the qubit has collapsed into (e.g., on state 214 and / or off state 212). For example, the controller 30 includes means such as a processing device 505, a memory 510, a driver controller element 515, an A / D converter 525, and / or similar, which cause a readout manipulation source to apply a readout beam to the qubit to be called, receive a signal indicating whether fluorescence of the qubit has been detected / observed in response to the application of the readout beam, and determine the quantum state of the qubit.

[0053] In step / operation 310, the controller 30 causes the readout qubit to be reinitialized. In various embodiments, reinitializing a qubit includes performing an unshelving procedure. In one exemplary embodiment, the unshelving procedure is performed only if, in step / operation 308, it is determined that the quantum state of the qubit has collapsed to a first state in the qubit space 210 and is therefore shelved in the readout procedure (e.g., no fluorescence was detected / observed). For example, the controller 30 may include means such as a processing device 505, a memory 510, a driver controller element 515, an A / D converter 525, and / or similar, which may, in some cases, cause the qubit to be reinitialized via an unshelving procedure. In various embodiments, reinitializing a qubit may include one or more additional steps and / or operations in addition to unshelving the qubit so that the qubit is in a known state in the qubit space 210.

[0054] Figure 4 illustrates a portion of the energy level diagram 400 for an exemplary atomic object that can be used as a qubit in a quantum computing system in one exemplary embodiment. When a qubit is shelved (for example, in step / operation 306), the qubit transitions to a stable state in the shelving manifold 230. An unshelving procedure is performed to unshelve the qubit and return it to the qubit space 210. In various embodiments, the unshelving procedure includes applying a third beam of a third wavelength λ3 and a fourth wavelength of a second wavelength λ2 in a manner that is simultaneous and / or at least partially overlapping. For example, the third beam is incident on the qubit for at least a fraction of the same time that the fourth beam is incident on the qubit. The third and fourth beams couple one or more stable states of the shelving manifold to one or more states of the transient manifold 420. In one exemplary embodiment, the third and fourth beams coherently couple one or more stable states of the shelving manifold to one or more states of the transient manifold 420. In various embodiments, the qubits rapidly collapse back to the qubit space 210 from one or more states of the transient manifold 420. In the embodiment shown, the transient manifold 420 has F=1 and F=2, [3 / 2] 3 / 2 Includes a manifold. In one exemplary embodiment, the third and fourth beams are applied such that the overlap time between the application of the third and fourth beams is in the range of 10 ns to 15 μs (e.g., 8 to 12 μs, 10 μs, and / or similar times).

[0055] For example, the controller 30 causes a third manipulation source to generate a third beam with a third wavelength λ3, and a second manipulation source (or a fourth manipulation source) to generate a fourth beam with a second wavelength λ2, thereby applying the third and fourth beams to the qubit simultaneously and / or in an at least partially overlapping manner. In various embodiments, the third wavelength λ3 is substantially equal to 976 nm, and the second wavelength λ2 is substantially equal to 3.4 μm. The qubit can then be collapsed (e.g., spontaneously) to return to the qubit space 210.

[0056] In one exemplary embodiment, the third and fourth beams may be applied in a phase-coherent manner. For example, the third and fourth beams may be applied with the same phase. In various embodiments, the third and fourth beams may not be applied in a coherent manner. For example, the third and fourth beams may be applied by a specific phase offset, an evolving phase offset, and / or the like. In one exemplary embodiment, the third and fourth beams may be applied at a specific angle between the propagation directions of the third and fourth beams. For example, the third and fourth beams may propagate in the same direction (e.g., substantially parallel propagation directions), in opposite directions (e.g., substantially antiparallel propagation directions), in orthogonal directions (e.g., substantially perpendicular propagation directions), or at any other angle between the propagation directions of the first and second beams, depending on the application. In one exemplary embodiment, the third and fourth beams may be applied by a specific polarization offset. For example, the third and fourth beams may be applied with the same polarization, opposite polarization (for example, the third beam may be right-handed linearly polarized and the fourth beam left-handed linearly polarized, or vice versa; the third beam may be right-handed circularly polarized and the fourth beam left-handed circularly polarized), and / or similar polarization, depending on the application.

[0057] Continuing to refer to Figure 3, in step / operation 312, the controller 30 may cause the quantum computer to continue executing the remainder and / or other parts of the quantum algorithm and / or circuit. For example, the controller 30 may include means such as a processing device 505, memory 510, driver controller element 515, A / D converter 525, and / or similar (see Figure 5) for executing additional and / or remaining parts of the quantum algorithm and / or circuit. For example, the controller 30 may continue to run a queue of commands that cause additional and / or remaining parts of the quantum algorithm and / or circuit to be executed. For example, adding and / or executing the rest of the quantum algorithm and / or circuitry may include initializing one or more qubits (e.g., placing one or more atomic objects into the qubit space 210), transporting at least some of the one or more qubits to one or more specific arrangements within the atomic object confinement device 300, executing one or more, one and / or two, and / or multi-qubit gates on at least some of the one or more qubits, reading out at least some of the one or more qubits, and / or similar operations. In one exemplary embodiment, the adding and / or rest of the quantum algorithm and / or circuitry may be modified based on the quantum state of the qubits determined in step / operation 308.

[0058] Technical advantages Various embodiments provide technical solutions to the technical problem of determining the quantum state of an atomic object when the atomic object is expected to be in a quantum state energetically close to another quantum state of the atomic object. In particular, various embodiments provide technical solutions for coherent shelving an atomic object that is in a first quantum state of a set of energetically close quantum states so that it can be determined whether the atomic object is in a second quantum state of a set of energetically close quantum states without limiting the determination by non-resonant errors. The coherent shelving described herein is significantly faster than conventional (non-coherent) shelving techniques. For example, conventional (non-coherent) shelving techniques are performed on a timescale of about 30 ms. The coherent shelving of various embodiments requires about 10–50 μs, i.e., three orders of magnitude faster than conventional (non-coherent) shelving. Various embodiments apply these technical solutions to the readout of qubits in a quantum computer where the qubits are atomic objects and the qubit space defines two qubit states separated by a small energy difference (e.g., less than 20 GHz). Therefore, various embodiments provide technical improvements to the field of art for precisely determining the quantum state of atomic objects. Some embodiments provide technical improvements to the field of art for reading out qubits from quantum computers (e.g., trap atomic object quantum computers that use hyperfine structures to define the qubit space).

[0059] Example Controller In various embodiments, the confinement device 300 is incorporated into a system (e.g., a quantum computer 110) that includes a controller 30. In various embodiments, the controller 30 is configured to control various elements of the system (e.g., a quantum computer 110). For example, the controller 30 may be configured to control a voltage source 50, a cryostat system and / or a vacuum system that controls the temperature and pressure within the cryostat and / or vacuum chamber 40, a manipulation source 60, a cooling system, and / or other systems that control environmental conditions (e.g., temperature, humidity, pressure, and / or similar) within the cryostat and / or vacuum chamber 40, and / or manipulate one or more atomic objects in the confinement device and cause a controlled evolution of the quantum state of the atomic objects. In various embodiments, the controller 30 may be configured to receive signals from one or more optical focusing systems.

[0060] As shown in Figure 5, in various embodiments, the controller 30 may include various controller elements, including a processing element 505, a memory 510, a driver controller element 515, a communication interface 520, an analog-to-digital converter element 525, and / or similar elements. For example, the processing element 505 may include a programmable logic device (CPLD), a microprocessor, a coprocessing entity, an application-specific instruction set processor (ASIP), an integrated circuit, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a programmable logic array (PLA), a hardware accelerator, other processing devices and / or circuits, and / or similar. The term "circuit" may refer to embodiments consisting solely of hardware, or a combination of hardware and computer program products. In one exemplary embodiment, the processing element 505 of the controller 30 includes and / or communicates with a clock.

[0061] For example, memory 510 may include non-temporary memory such as volatile and / or non-volatile memory storage, such as one or more of the following: hard disk, ROM, PROM, EPROM, EEPROM, flash memory, MMC, SD memory card, memory stick, CBRAM, PRAM, FeRAM, RRAM, SONOS, racetrack memory, RAM, DRAM, SRAM, FPM DRAM, EDO DRAM, SDRAM, DDR SDRAM, DDR2 SDRAM, DDR3 SDRAM, RDRAM, RIMM, DIMM, SIMM, VRAM, cache memory, register memory, and / or similar. In various embodiments, memory 510 may store a queue of commands to be executed to cause quantum algorithms and / or circuits to be executed (e.g., an executable queue), qubit records corresponding to the qubits of a quantum computer (e.g., in a qubit record datastore, qubit record database, qubit record table, and / or similar), calibration tables, computer program code (e.g., one or more computer languages, dedicated controller languages, and / or similar languages), and / or similar. In one exemplary embodiment, the execution of at least a portion of the computer program code stored in memory 510 (for example, by processing element 505) causes the controller 30 to perform one or more steps, operations, processes, procedures, and / or similar as described herein to perform a qubit readout procedure including a shelving procedure (and an unshelving procedure).

[0062] In various embodiments, the driver controller element 510 may include one or more driver and / or controller elements, each configured to control one or more drivers. In various embodiments, the driver controller element 510 may comprise drivers and / or driver controllers. For example, a driver controller may be configured to cause one or more corresponding drivers to be operated according to executable instructions, commands, and / or similar, scheduled and executed by the controller 30 (e.g., by the processing element 505). In various embodiments, the driver controller element 515 may enable the controller 30 to operate a voltage source 50, a manipulation source 60, a cooling system, and / or similar. In various embodiments, the drivers may be a laser driver, a vacuum component driver, a driver for controlling the flow of current and / or voltage applied to electrodes used to maintain and / or control the trapping potential of the confinement device 300 (and / or other drivers for providing a driver operating sequence to the potential generating elements of the confinement device), a cryostat and / or vacuum system component driver, a cooling system driver, and / or similar. In various embodiments, the controller 30 includes means for transmitting and / or receiving signals from one or more photodetector components (e.g., an optical system focusing system). For example, the controller 30 may include one or more analog-to-digital converter elements 525 configured to receive signals from one or more photodetector components (e.g., photodetectors in an optical system focusing system), a calibration sensor, and / or similar.

[0063] In various embodiments, the controller 30 may include a communication interface 520 for interfaceing with and / or communicating with the computing entity 10. For example, the controller 30 may include a communication interface 520 for receiving executable instructions, command sets, and / or similar from the computing entity 10 and for providing the computing entity 10 with outputs received from the quantum computer 110 (e.g., from the optical focusing system) and / or the results of processing those outputs. In various embodiments, the computing entity 10 and the controller 30 may communicate via direct wired and / or wireless connections and / or via one or more wired and / or wireless networks 20.

[0064] Exemplary Computing Entity Figure 6 is an exemplary schematic diagram of an exemplary computing entity 10 that can be used in combination with embodiments of the present invention. In various embodiments, the computing entity 10 is configured to allow a user to provide input to a quantum computer 110 (for example, through a user interface of the computing entity 10), receive, display, analyze, and / or perform similar operations on outputs from the quantum computer 110.

[0065] As shown in Figure 6, the computing entity 10 may include an antenna 612, a transmitter 604 (e.g., wireless), a receiver 606 (e.g., wireless), and a processing element 608 that provides and receives signals to the transmitter 604 and receiver 606, respectively. The signals provided to and received from the transmitter 604 and receiver 606 may include signaling information / data according to applicable wireless system air interface standards for communicating with various entities such as the controller 30, other computing entities 10, and / or similar. In this regard, the computing entity 10 may be able to operate with one or more air interface standards, communication protocols, modulation types, and access types. For example, the computing entity 10 may be configured to receive and / or provide communications using wired data transmission protocols such as Fiber Distributed Data Interface (FDDI), Digital Subscriber Line (DSL), Ethernet, Asynchronous Transfer Mode (ATM), Frame Relay, Data Over Cable Service Interface Specification (DOCSIS), or any other wired transmission protocol.Similarly, computing entity 10 supports General-Purpose Packet Radio System (GPRS), Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA2000), CDMA2000 1X (1xRTT), Wideband Code Division Multiple Access (WCDMA®), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), Long-Term Evolution (LTE), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), Evolved Data Optimized (EVDO), High Speed ​​Packet Access (HSPA), High Speed ​​Downlink Packet Access (HSDPA) IEEE 802. It may be configured to communicate over a wireless external communication network using any of the following protocols: 11 (Wi-Fi®), Wi-Fi® Direct, 802.16 (WiMAX), Ultra Wideband (UWB), Infrared (IR) protocol, Near Field Communication (NFC) protocol, Wibree, Bluetooth® protocol, Wireless Universal Serial Bus (USB) protocol, and / or any other wireless protocol.Computing entity 10 may communicate using such protocols and standards as Border Gateway Protocol (BGP), Dynamic Host Configuration Protocol (DHCP), Domain Name System (DNS), File Transfer Protocol (FTP), Hypertext Transfer Protocol (HTTP), HTTP over TLS / SSL / Secure, Internet Message Connection Protocol (IMAP), Network Time Protocol (NTP), Simple Mail Transfer Protocol (SMTP), Telnet, Transport Layer Security (TLS), Secure Sockets Layer (SSL), Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Datagram Congestion Control Protocol (DCCP), Stream Control Transmission Protocol (SCTP), Hypertext Markup Language (HTML), and / or similar.

[0066] Through these communication standards and protocols, computing entity 10 can communicate with various other entities using concepts such as unstructured supplemental service information / data (USSD), short message service (SMS), multimedia messaging service (MMS), dual-tone multi-frequency signaling (DTMF), and / or subscriber identification module dialer (SIM dialer). Computing entity 10 can also download changes, add-ons, and updates to its firmware, software (including, for example, executable instructions, applications, and program modules), and operating system.

[0067] The computing entity 10 may also include user interface devices, including one or more user input / output interfaces (for example, a display 616 and / or speaker / speaker driver coupled to the processing element 608, and a touchscreen, keyboard, mouse, and / or microphone coupled to the processing element 608). For example, a user output interface may be configured to provide applications, browsers, user interfaces, interfaces, dashboards, screens, web pages, pages, and / or similar words used interchangeably herein, which run on and / or are accessible through the computing entity 10, for the purpose of displaying or audibly presenting information / data, and for interactive operation via one or more user input interfaces. A user input interface may comprise any of a number of devices that enable the computing entity 10 to receive data, such as a keypad 618 (hard or soft), a touch display, a voice / speech or motion interface, a scanner, a reader, or other input device. In embodiments including a keypad 618, the keypad 618 may include (or trigger) a set of keys that can be activated to provide a full set of alphabetic keys or a full set of alphanumeric keys, and may include conventional numeric keys (0-9) and related keys (#, *), and other keys used to operate the computing entity 10. In addition to providing input, the user input interface can be used to activate or deactivate several functions, such as a screen saver and / or sleep mode. Through such input, the computing entity 10 can collect information / data, user interactions / inputs, and / or the like.

[0068] Computing entity 10 may also include volatile storage or memory 622 and / or non-volatile storage or memory 624, which may be embedded and / or removable. For example, non-volatile memory may be ROM, PROM, EPROM, EEPROM, flash memory, MMC, SD memory card, memory stick, CBRAM, PRAM, FeRAM, RRAM, SONOS, racetrack memory, and / or similar. Volatile memory may be RAM, DRAM, SRAM, FPM DRAM, EDO DRAM, SDRAM, DDR SDRAM, DDR2 SDRAM, DDR3 SDRAM, RDRAM, RIMM, DIMM, SIMM, VRAM, cache memory, register memory, and / or similar. Volatile and non-volatile storage or memory may store databases, database instances, database management system entities, data, applications, programs, program modules, scripts, source code, object code, bytecode, compiled code, interpreter code, machine code, executable instructions, and / or similar to implement the functionality of computing entity 10.

[0069] conclusion Many modifications and other embodiments of the invention described herein will be conceivable to those skilled in the art who benefit from the teachings presented in the foregoing description and the accompanying drawings. It will be understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the accompanying claims. Although certain terms are used herein, they are used only in a general and descriptive sense and are not intended to be limiting. [Explanation of symbols]

[0070] 10 Computing Entities 20. Wired and / or wireless networks 30 controllers 40 Cryostat and / or vacuum chamber 50 Voltage source 60 Manipulation Sources 100 Quantum Computing Systems 110 Quantum Computers 200 Energy Level Diagram 210-qubit space 212 First qubit state 214 Second qubit state 220 Intermediate Manifold 230 Shelving Manifold 300 Atomic Object Confinement Device 400 Energy Level Diagram 420 Temporary Manifold 505 Processing Devices 510 memory 515 Driver Controller Elements 520 Communication Interfaces 525 A / D converter 604 Transmitter 606 Receiver 608 processing elements 612 Antenna 616 displays 618 Keypad

Claims

1. 1. A controller for a trapped ion quantum computer, comprising: The controller comprises at least one processing device, the at least one processing device in communication with at least one manipulation source driver; The at least one processing device may further include: incident a first beam at a first wavelength and a second beam at a second wavelength on a quantum bit, the first wavelength and the second wavelength configured to couple a state of quantum space of the quantum bit to a stable state, the stable state having a lifetime longer than a length of time required to perform a read operation, the first beam and the second beam being generated by at least one manipulation source operated by the at least one manipulation source driver; and directing a readout beam to the quantum bit.

2. the at least one processing device is in communication with the photodetector; The at least one processing device may further include: receiving a signal from the photodetector, the signal corresponding to a result of the readout beam being incident on the quantum bit; and determining a state of the quantum bit based on the signal.

3. 2. The controller of claim 1, wherein the at least one processing device is configured to cause a readout beam to be incident on the quantum bit and monitor a signal generated by a photodetector to determine whether the quantum bit fluoresces in response to the readout beam being incident on the quantum bit to perform the readout operation.

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