578 results about "Qubit" patented technology

The invention discloses a quantum bit mapping optimization method for hardware guidance and fidelity perception and a related device, and belongs to the field of quantum computing, and the method comprises the steps: defining each node in a hardware coupling graph of a target quantum processor as an initial community; evaluating all adjacent community pairs according to a reward function defined based on modularity and fidelity of candidate communities, selecting an optimal community pair for fusion, and taking the community with the largest current scale as an optimal candidate area; iteratively executing a community fusion step until a converged single community is obtained; and selecting an optimal candidate region with the physical quantum bit number greater than or equal to the logic quantum bit number of the quantum circuit to be mapped and the minimum scale, and outputting a mapping sub-graph. According to the method, through a recursive community fusion strategy, the operation range of the solver is restrained in a subspace with the scale greatly reduced and the quality better, the problem of combinatorial explosion caused by global search is fundamentally avoided, and the calculation overhead is greatly reduced.

The invention relates to the technical field of quantum computing, and provides a linear complexity quantum state preparation method based on tensor decomposition and a quantum circuit construction system.The high-dimensional tensor is decomposed into a series of low-rank core tensors through continuous singular value decomposition, each core tensor in a core tensor sequence is expanded into a unitary matrix, and the unitary matrix is used as a quantum circuit; the unitary matrix sequence is mapped to quantum lines coupled using adjacent qubits, and the quantum lines are run to prepare a target quantum state. Based on this, the line generated by the method can approximately or accurately prepare a target quantum state only by coupling adjacent quantum bits, and is perfectly adaptive to quantum chips of linear or grid topologies such as superconducting and semiconductor quantum dots and the like.

Quantum computers with a limited number of input qubits are used to perform machine learning processes having a far greater number of trainable features. A list of features of a field are divided into a plurality of feature groups. Each of the feature groups includes a respective group of some, but not all, of the features. A first machine learning process is performed to train a first instance of a quantum computer model, where the feature groups are used as inputs. Based on the first machine learning process being performed, a subset of the feature groups is selected for a second machine learning process. Thereafter, the second machine learning process is performed to train one or more second instances of the quantum computer model. The individual features of the selected subset of the feature groups are used as inputs for the second instances of the quantum computer model.

An information processing apparatus causes a quantum computer to perform a first gate operation in accordance with an ancilla state generation circuit representing a procedure of generating a code including a logical qubit representing an ancilla state and a gauge qubit representing a redundant degree of freedom other than the ancilla state. Next, the information processing apparatus causes the quantum computer to perform a second gate operation in accordance with an error detection circuit representing a procedure of detecting an error occurring in a plurality of physical qubits constituting the code generated by the first gate operation. Then, the information processing apparatus determines the presence or absence of the error on the basis of a measurement value obtained by the second gate operation, the measurement value indicating the state of the gauge qubit.

The invention discloses a quantum circuit conversion method and system, electronic equipment and a storage medium, and relates to the technical field of quantum circuit conversion, and the method comprises the steps: extracting a feature vector of a logic quantum circuit based on initial quantum bit mapping; the feature vector is input into a pre-trained decision tree, recommendation parameters of a line conversion algorithm are obtained, the decision tree is constructed by a training set, and the feature vector of each sample corresponds to the optimal parameter of the decision tree, namely the parameter with the minimum number of physical line gates; and configuring a line conversion algorithm by using recommended parameters, converting a logic line into a physical line, and ensuring that all two quantum bit gates meet quantum computer connected graph constraints and are equivalent in function. According to the method, adaptive parameter configuration can be achieved through the feature vectors and the decision tree, the line conversion quality is effectively improved, the number of physical line gates is remarkably reduced, and the quantum program execution efficiency is improved on the premise that function equivalence and connectivity are guaranteed.

Methods and systems for mitigating the effects of defects in a quantum processor are provided. A mitigation system includes a quantum processor comprising a plurality of qubits. The system includes a light emitting source that can be tuned to produce light pulses of different wavelengths. The system includes an array of bandpass filters. Each bandpass filter is aligned with a qubit on the quantum processor and has a unique pass band. The system may include a controller configured to receive a selection of a qubit and to tune the light emitting source to emit a light pulse having a wavelength that falls within a range of a bandpass filter that is aligned with the selected qubit. The light pulse is used to scramble an ensemble of strongly coupled two-level system (TLS) in the processor.

A method of method of classifying data is disclosed. The method comprises manipulating quantum states of qubits of a quantum computing device based on a first copy of a test vector, a second copy of the test vector, a first training vector and a second training vector, so as to load a modified first copy of the test vector, a modified second copy of the test vector, a modified first training vector and a modified second training vector onto the quantum computing device, wherein the magnitude of the angle between the modified first copy of the test vector and the modified first training vector is equal to the magnitude of the angle between the first copy of the test vector and the first training vector, and where the magnitude of the angle between the modified second copy of the test vector and the modified second training vector is equal to the magnitude of the angle between the second copy of the test vector and the second training vector. The method also comprises performing quantum interference between the modified first copy of the test vector and the modified second copy of the test vector, and the modified first training vector and the modified second training vector, to provide modified quantum states of the qubits, performing a measurement on one or more of the qubits, and classifying the test vector based on the measurement.

A system for data content feature extraction and evaluation using a hybrid quantum and classical neural network is disclosed. The system receives an input vector that represents digital content and generates a first quantum state vector for the input vector. The system generates a second quantum state vector by performing a quantum convolution operation on the first quantum state vector. The system initiates a second feature vector by mapping each quantum bit within the second quantum state vector to a respective numerical value. The system generates an output feature vector by performing a convolution operation on the second feature vector. The system evaluates the output feature vector by comparing the output feature vector with an expected vector. The system determines that the output feature vector corresponds to the expected vector. In response, the system determines that the output feature vector represents the digital content.

A method of generating an entangled state for quantum computing includes providing respective qubit from a plurality of Bell pairs to a plurality of probabilistic entangling gates according to a predefined graph structure. The success probability for generating respective qubits of the entangled state using the probabilistic entangling gates is greater than a percolation threshold for the predefined graph structure.

The present invention relates to a quantum computer comprising NV centers in diamond as quantum bits, nuclear spins of nuclei strongly coupled to the NV centers, strongly constrained by these NV centers, as nuclear quantum bits (hereinafter referred to as strong nuclear quantum bits), and nuclear spins, weakly constrained by these NV centers, of nuclei weakly coupled to the NV centers as nuclear qubits (hereinafter referred to as weak nuclear qubits). The resonance energy for coupling the weakly coupled nuclear spins of the nuclei weakly coupled to the respective NV centers depends only weakly on the respective spin state of the electron configuration of the NV centers weakly coupled to that nuclear spin. The control mode of the quantum computer on nuclear spin under weak constraint of the NV center is different from the control mode of the quantum computer on nuclear spin under strong constraint of the NV center. To this end, the quantum computer preferably has a kernel qubit database that stores information about whether the kernel qubits are strongly coupled or weakly coupled.

Aspects of the present disclosure relate generally to systems and methods for detecting change in images using a quantum information processing (QIP) system. The method includes implementing a quantum circuit in the QIP system, the quantum circuit comprising at least an ancilla qubit denoted as |a> and qubits denoted as image qubit conditions on a |0> state and a |1> state of the ancilla qubit |a>. The method also includes loading a reference image and a test image onto image qubits controlled on the |0> state and the |1> state of the ancilla qubit |a> in the quantum circuit. The method further includes determining a state of the image qubits after measuring |1> on the ancilla qubit for a predetermined number of times, wherein the reference image is detected to be different from the test image when the state of the ancilla qubit measures |1>.

Provided is a quantum computing method for obtaining an optimal solution of a problem with multiple discrete variables, wherein the problem is represented by a cost function, the method comprising:—generating a graph structure from the cost function,—dividing the graph structure into at least two disjunct subgraph structures, wherein each subgraph structure comprises a subset of the multiple variables,—mapping each subgraph structure to a local cost function represented as local cost Hamiltonian,—determining, for each local cost Hamiltonian, all eigenstates corresponding to an energy below a predetermined cut off energy using a quantum processing device, wherein each variable of the subset of multiple variables is represented by a qubit of the quantum processing device,—recombining the determined eigenstates, and-approximating a ground state from the recombined eigenstates, wherein the ground state represents the optimal solution.

Aspects of the present disclosure relate generally to systems and methods for optimizing an implementation of a quantum chemistry task in a quantum circuit. The method includes obtaining a chemistry task presented as a Hamilton to implement in a Variational Quantum Eigensolver (VQE) circuit. The method also includes mapping the chemistry task to a qubit space of the VQE circuit with Unitary Coupled Cluster with Single and Double excitations (UCCSD) ansatz. The method also includes decomposing the fermionic excitations to Givens rotations and controlled-Z (CZ) gates by passing exponentiated Pauli forms in the VQE circuit to a cloud compiler. The method further includes after commuting the CZ gates through Givens rotations, cancelling the commuted CZ gates. The method further includes dropping CZ gates at the beginning and the end of the quantum circuit.

Systems and methods are described for quantum information retrieval. An example system may include a quantum cloning unit, a photon number splitting (PNS) unit, and a variable-strength measurement unit to enhance the accuracy and reliability of quantum state estimations without introducing substantial decoherence. The quantum cloning unit may be used to generate approximate clones of a qubit. If the information is encoded in a multi-photon state resulting in a multi-photon state qubit, then the photon number splitting (PNS) unit may be used to intercept the multi-photon state and reflect a single photon from the multi-photon state, which may then be subjected to quantum cloning. These qubits and qubit clones may then be subjected to variable-strength measurements, which provides detailed analysis with minor disturbance to quantum properties such as superposition and entanglement.

An example computer-implemented method for calibrating a qubit of a quantum device is disclosed. The example method includes obtaining a candidate calibration model for calibrating an operating characteristic of the qubit. The example method includes determining, using one or more quantum device models, a simulated quantum device performance metric associated with implementation of the candidate calibration model based on log data descriptive of observed qubit operating characteristics and associated observed quantum device performance metrics.

Quantum reservoir computation is provided. A first feature vector is determined from input data. A plurality of qubits is configured in an initial configuration according to the first feature vector, wherein a detuning, Rabi frequency, phase, and / or position of each of the plurality of qubits is determined by a respective one of the values of the first feature vector. The plurality of qubits is evolved for a first time. The plurality of qubits is measured to obtain first measurements after the first time. The plurality of qubits is returned to the initial configuration. The plurality of qubits is evolved for a second time. The plurality of qubits is measured to obtain second measurements after the second time. A second feature vector is determined from the first and second measurements. The second feature vector is provided to a decoder and a characteristic of the input data is obtained therefrom.

A system for scalable two-dimensional surface code comprises four sub-lattices of qubits, each selectively controlled by a set of analog lines. Eight sets of analog lines selectively control eight sets of inter-qubit couplers. The qubits and couplers have response homogenization devices comprising control structures to apply analog signals and DACs to apply static bias to qubits and couplers. A second surface code layer compensates for defective qubits. A quantum processor and a method of moving data within a quantum processor are described. The quantum processor has quantum logic units with a plurality of physical qubits and couplers. The logic unit has a plurality of logical qubit blocks making up 2-local interaction registers. A shift register block with one or more logical qubit blocks and merge blocks connecting adjacent logical qubit blocks are provided. The shift register block is selectively communicatively coupled to 2-local interaction registers by a merge block.

In a general aspect, a multi-qubit quantum logic gate for a multi-qubit hardware-efficient stabilizer measurement is performed. In some implementations, a superconducting quantum processing unit includes a stabilizer check qubit device and two or more data qubit devices operably coupled to the stabilizer check qubit device through respective tunable-frequency coupler devices. A method includes applying a multi-qubit quantum logic gate on the stabilizer check qubit device and the two or more data qubit devices. Applying the multi-qubit quantum logic gate includes evolving the stabilizer check qubit device and the two or more data qubit devices under an interaction Hamiltonian with a plurality of terms. Each of the plurality of terms corresponding to an interaction between the stabilizer check qubit device and a respective one of the two or more data qubit devices, includes a phase combined with a Pauli operator applied to the stabilizer check qubit device and the Pauli operator applied to the respective one of the two or more data qubit devices.

A high-temperature superconducting qubit implements a quantum mechanical two-level system. The high-temperature superconducting qubit comprises a first superconductor, a second superconductor, and an overlap region. The first superconductor comprises a first high-temperature superconductor material. The second superconductor comprises a second high-temperature superconductor material. In the overlap region, at least a first section of the first surface and at least a second section of the second surface overlap, the first section and the second section are arranged in parallel at a distance corresponding to a predefined distance, and the first orientation and the second orientation are arranged with an angle corresponding to a predefined angle. The high-temperature superconducting qubit comprises a Josephson junction between the first high-temperature superconductor material and the second high-temperature superconductor material. The Josephson junction provides the quantum mechanical two-level system of the high-temperature superconducting qubit.

Aspects of the present disclosure relate generally to systems and methods for use in the implementation and / or operation of quantum information processing (QIP) systems, and more particularly, to the use of qubit feedback for noise cancellation in quantum elements and / or quantum computations in QIP systems.

The invention relates to a quantum system (1) for stabilizing a cat qubit comprising: - a command circuit (5) including a microwave source (11) and a DC voltage source (13), and - a non-linear superconducting quantum circuit (3) including a non-linear element (7) comprising a Josephson junction, a first and a second resonant portions respectively having a first mode with a first resonant frequency fa and a second mode with a second resonant frequency fb. The non-linear superconducting quantum circuit (3) stabilizes a two-dimensional manifold hosting the cat qubit when: • the microwave source (11) delivers microwave radiation at a frequency equal to fb to the second resonant portion to drive the second mode, and • the DC voltage source (13) delivers DC voltage to bias the non-linear element (7), with the delivered DC voltage having a value inducing a microwave oscillation having a frequency equal to |2fa - fb|.

A system and method for estimating values of an operator, such as energy levels of a Hamiltonian, is disclosed. The estimation is performed in a way such that the runtime of performing the estimation is independent of a complexity of the operator, e.g., a number of terms in the Hamiltonian. Also, errors can be statistically suppressed by performing additional sampling, due to a lack of biased error in the estimator. Additionally, samples may be tested using only a single ancilla qubit.

Methods and systems for controlling a system of superconducting qubits using single flux quantum (SFQ) pulse schedule is provided. The single flux quantum (SFQ) pulse schedule may comprise on-ramp, off-ramp, and resonant parts, wherein the frequency of a single flux quantum (SFQ) pulse clock is at about a multiple of a qubit frequency. The method may include: providing a system of one or more qubits; delivering a single flux quantum (SFQ) pulse to each of the one or more qubits, the single flux quantum (SFQ) pulse being capable of influencing a quantum state of a qubit; obtaining at least one single flux quantum (SFQ) pulse schedule for the one or more qubits, each schedule comprising on-ramp, resonant, and off-ramp parts; and implementing the at least one single flux quantum (SFQ) pulse schedule for the one or more qubits.

In a method for implementing a quantum state factory in a quantum circuit, it is determined for at least one qubit that the qubit is an idle and clean qubit within a sub-circuit of the quantum circuit. The qubit is idle if no quantum operation operates within the sub-circuit of the quantum circuit on the qubit. The qubit is clean if the qubit does not store information which is used within or after the sub-circuit of the quantum circuit. The at least one idle and clean qubit is assigned within the sub-circuit of the quantum circuit to a quantum state factory for generating at least one quantum state. The quantum state factory is implemented within the sub-circuit of the quantum circuit.

The embodiment of the invention provides a parameter space degree of freedom determination method and device, electronic equipment and a storage medium, and the scheme is as follows: according to a first working frequency and a second working frequency corresponding to a first quantum bit and a second quantum bit under the condition that the frequency detuning is 0, and a third working frequency of an adjustable coupler under a preset gate length, determining the degree of freedom of a parameter space; calculating target coupling strength; according to periodic quantum logic gate operations on the first quantum bit and the second quantum bit under different frequency detuning conditions, obtaining a first corresponding relation between frequency detuning and a leakage rate, and obtaining a second corresponding relation between frequency detuning and a preset condition phase; and based on the first corresponding relation and the second corresponding relation, obtaining first detuning and second detuning corresponding to the lowest leakage rate under the target phase as target detuning parameters. According to the technical scheme provided by the embodiment of the invention, the influence of the distortion of the residual short time scale on the magnetic flux control line on the quantum calculation process can be avoided, so that the fidelity of quantum calculation is improved.

Aspects of the present disclosure relate generally to systems, devices, methods, and computer-program products for use in the implementation and / or operation of quantum information processing (QIP) systems, and more particularly, for circuit embedding in a quantum computer having reconfigurable qubit registers.

Quantum operations can be simulated on a classical processing system using a quantum virtual machine (QVM). The QVM receives a quantum virtual state including a virtual wavefunction of n qubits. The virtual wavefunction is represented by probability amplitudes stored in a memory location of the classical processing system. The QVM simulates a received quantum operation by determining a set of virtual partial wavefunctions, accessing probability amplitudes for the virtual partial wavefunctions, and executing the quantum operation on the sub-bitstrings. The QVM can measure the result of the quantum operation, add noise, share the virtual wavefunction, or generate efficient machine instructions when simulating the quantum operation.

A quantum method includes providing a plurality of atoms including first and second 171Yb atoms spatially separated from one another and exciting the first 171Yb atom to a target Rydberg state without exciting the second 171Yb atom to the target Rydberg state. A quantum logic gate includes a first 171Yb qubit excited to a target Rydberg state and a second 171Yb qubit spatially separated from the first 171Yb qubit, wherein the second 171Yb qubit is not excited to the target Rydberg state while the first 171Yb qubit is excited to the target Rydberg state. A quantum computing system includes a chamber housing a plurality of atoms including first and second 171Yb atoms spatially separated from one another and at least one gate laser source configured to excite the first 171Yb atom to a target Rydberg state without exciting the second 171Yb atom to the target Rydberg state.

Aspects provide systems and methods for utilizing quantum computing systems for processing of data generated by quantum sensor. For example, magnetic field data may be captured from a brain using a quantum sensor array. This magnetic field data may then be processed using a quantum computing apparatus including a plurality of qubits in order to generate a model of the brain.