This application discloses a fault tolerant computation method and device for a quantum Clifford circuit with reduced resource requirement. The method includes decomposing a quantum Clifford circuit into s logic Clifford circuits and preparing auxiliary quantum states corresponding to the s logic Clifford circuits. For each logic Clifford circuit, the method further includes teleporting an input quantum state corresponding to the logic Clifford circuit to an auxiliary qubit, processing a quantum state obtained after the teleportation by the logic Clifford circuit to obtain a corresponding output quantum state; measuring a corresponding error symptom based on the input quantum state and the auxiliary quantum state; and performing error correction on the output quantum state according to the error symptom to obtain an error-corrected output quantum state.

Systems and methods for calibrating a qubit parameter for a qubit in a quantum computing system are provided. In one example, a method includes obtaining, by one or more computing devices, data associated with a set of one or more qubit parameters for a qubit in a quantum computing system. The method includes obtaining, by the one or more computing devices, calibration data associated with at least one qubit parameter in the set of one or more qubit parameters. The method includes determining, by the one or more computing devices, a value for the at least one qubit parameter based at least in part on the calibration data using a de-corrupting autoencoder.

Systems and methods for calibrating a qubit parameter for a qubit in a quantum computing system are provided. In one example, a method includes obtaining, by one or more computing devices, data associated with a set of one or more qubit parameters for a qubit in a quantum computing system. The method includes obtaining, by the one or more computing devices, calibration data associated with at least one qubit parameter in the set of one or more qubit parameters. The method includes determining, by the one or more computing devices, a value for the at least one qubit parameter based at least in part on the calibration data using a de-corrupting autoencoder.

The is provided a computer-implemented method for generating a quantum circuit from a Unitary Coupled Cluster (UCC) Ansatz, wherein the Ansatz represents an excitation of a reference state by a parameterised operator including excitation operators, and wherein the Ansatz includes multi-qubit Pauli operators that are determined from each excitation operator. The method comprises: partitioning the Pauli operators into mutually commuting sets and sequencing the Pauli operators by set; generating Pauli gadgets from the Pauli operators by Trotterization, wherein the Pauli gadgets have a same sequencing by set as the Pauli operators; diagonalising each set of Pauli gadgets to convert the Pauli gadgets into phase gadgets; and transforming the phase gadgets into one- and two-qubit native gates to generate the quantum circuit. Moreover, there is also provided a system that is configured to implement the method.

The is provided a computer-implemented method for generating a quantum circuit from a Unitary Coupled Cluster (UCC) Ansatz, wherein the Ansatz represents an excitation of a reference state by a parameterised operator including excitation operators, and wherein the Ansatz includes multi-qubit Pauli operators that are determined from each excitation operator. The method comprises: partitioning the Pauli operators into mutually commuting sets and sequencing the Pauli operators by set; generating Pauli gadgets from the Pauli operators by Trotterization, wherein the Pauli gadgets have a same sequencing by set as the Pauli operators; diagonalising each set of Pauli gadgets to convert the Pauli gadgets into phase gadgets; and transforming the phase gadgets into one- and two-qubit native gates to generate the quantum circuit. Moreover, there is also provided a system that is configured to implement the method.

This disclosure relates to a method and system for efficiently and analytically generating spectra associated with transitions between thermal states in a multi-mode bosonic system using a classical algorithm to compute Fourier components of the transition spectra of the multi-mode bosonic system based on a representation space sampling method inspired by quantum Gaussian boson sampling followed by an inverse Fourier transform. The disclosed method and system particularly apply to efficient estimation of molecular vibronic spectra. For example, an exact solution of the Fourier components of molecular vibronic spectra at zero temperature may be analytically computed in a representation space by using, for example, a positive P-representation of the multi-mode bosonic vibronic quantum states of the molecule. Such a method may be further applied to more general vibronic spectroscopy, such as computing molecular vibronic spectra at finite temperatures by introducing additional auxiliary bosonic modes and computing vibronic spectra associated with non-thermal states, such as Fock states.

This disclosure relates to a method and system for efficiently and analytically generating spectra associated with transitions between thermal states in a multi-mode bosonic system using a classical algorithm to compute Fourier components of the transition spectra of the multi-mode bosonic system based on a representation space sampling method inspired by quantum Gaussian boson sampling followed by an inverse Fourier transform. The disclosed method and system particularly apply to efficient estimation of molecular vibronic spectra. For example, an exact solution of the Fourier components of molecular vibronic spectra at zero temperature may be analytically computed in a representation space by using, for example, a positive P-representation of the multi-mode bosonic vibronic quantum states of the molecule. Such a method may be further applied to more general vibronic spectroscopy, such as computing molecular vibronic spectra at finite temperatures by introducing additional auxiliary bosonic modes and computing vibronic spectra associated with non-thermal states, such as Fock states.

A qubit memory cell having a thin, optically transparent, metal surface gate that laterally fits into the corresponding region of the memory cell, while not being in direct contact with the perimeter of the region. The surface gate may have apertures to accommodate therein the dot-like control electrodes of the qubit and enable the corresponding electrical overpass bridges to be connected to those dot-like control electrodes. The thickness of the surface gate may be selected such as to let a substantial portion of light impinging thereupon penetrate to the underlying surface of the substrate. In at least some embodiments, the electrical-interconnect structure of the memory cell may be designed to enable separate electrical biasing of the surface gate, e.g., independent of the electrical biasing of some other electrodes of the memory cell. Advantageously, such a surface gate may significantly reduce detrimental clumping of charge carriers in the memory cell.

A qubit memory cell having a thin, optically transparent, metal surface gate that laterally fits into the corresponding region of the memory cell, while not being in direct contact with the perimeter of the region. The surface gate may have apertures to accommodate therein the dot-like control electrodes of the qubit and enable the corresponding electrical overpass bridges to be connected to those dot-like control electrodes. The thickness of the surface gate may be selected such as to let a substantial portion of light impinging thereupon penetrate to the underlying surface of the substrate. In at least some embodiments, the electrical-interconnect structure of the memory cell may be designed to enable separate electrical biasing of the surface gate, e.g., independent of the electrical biasing of some other electrodes of the memory cell. Advantageously, such a surface gate may significantly reduce detrimental clumping of charge carriers in the memory cell.

A method for determining a cryptographic key is carried out in a data processing system, and comprises: providing a plaintext and a ciphertext determined from the plaintext using a cryptographic key and a cryptographic procedure which comprises cryptographic operations; for each cryptographic operation of the cryptographic procedure, providing at least one intermediate relation which comprises an intermediate equation and/or an intermediate inequality; determining an optimization problem comprising: the plaintext and the ciphertext; at least one optimization expression assigned to a round of the cryptographic procedure; and optimization variables comprising state variables of the cryptographic procedure and a cryptographic key variable; wherein the at least one optimization expression is determined from the at least one intermediate relation and comprises at least one preceding state variable assigned to a preceding round. The method further comprises: solving the optimization problem and determining the cryptographic key from an optimizing value of the cryptographic key variable.