Backends

Qristal can execute circuits on a wide variety of hardware and simulator backends.

Hardware backends

Parallelism

Note that Qristal supports parallel execution on multiple quantum hardware devices, using MPI. To make use of this feature, each MPI process must be configured to use a different physical hardware accelerator. For maximum performance, we recommend using the same model of quantum hardware device for each accelerator. See session::mpi_accelerators for more info.

Quantum Brilliance

Description: Quantum Brilliance room-temperature QPUs based on diamond NV technology. Includes all rack-mounted Quantum Development Kit (QDK) and desktop quantum computer (DQC) iterations, as well as virtualised instances.

Provided by: Open-source Qristal SDK

Executes on: A local or remote Quantum Brilliance quantum computer.

Parameters:

  • exclusive_access: boolean, optional. Request exclusive use of the hardware device before attempting to execute any circuits on it. If this flag is set true and the hardware device accepts the request, it will accept circuits only from the current instance of Qristal for the duration of exclusive mode. Default: False
    The following option is required if exclusive_access = true:

    • exclusive_access_token: string. The JSON web token (JWT) required to execute circuits on the device during exclusive mode.

  • init: vector of integers, optional. Values to initialise the qubits to. Indexing of this list matches the indices of qubits in circuits. Default: all qubits initialised to 0.

  • poll_secs: floating-point, required. Interval in seconds to wait between queries to the device about the completion status of a running circuit.

  • poll_retries: integer, required. Maximum number of times to query the device about the completion status of a running circuit. If this many unsuccessful queries are made, return a timeout error.

  • url: string, required. The URL of the hardware device (or its circuit server qcstack, if qcstack is not running on the hardware device itself).

  • use_default_contrast_settings: boolean, optional. Run with the default measurement contrast settings defined by the hardware device. Default: True
    The following options are required if use_default_contrast_settings = false:

    • init_contrast_threshold: floating-point. The contrast threshold to use for initialisation during post-selection. Shots are only accepted if qubit initialisation using single-shot readout results in a photoluminescence contrast exceeding this value. The highest practically usable setting is about 0.2.

    • qubit_contrast_thresholds: { integer keys \(\rightarrow\) floating-point values }. The contrast threshold to apply on a per-qubit basis during final readout. Shots are only accepted if single-shot readout produces a photoluminescence contrast exceeding this value. The highest practically usable setting is about 0.2. Indexing of this list matches the indices of qubits in circuits.

These parameters are set in the remote_backends.yaml configuration file, under the top-level heading corresponding to the named QB hardware resource to which they should be applied. To use an alternative file, assign its path to the qristal.session.remote_backend_database_path attribute.

Example: tests/qcstack.

Notes:

Entries in remote_backends.yaml may contain environment variables, in order to facilitate interoperability with job schedulers such as qtil and SLURM, e.g.

qpu1:
  url: $QTIL_qpus_1_IP
  exclusive_access: true
  exclusive_access_token: $QTIL_qpus_1_TOKEN
  ...

where $QTIL_qpus_1_IP and $QTIL_qpus_1_TOKEN are the device IP and JWT provided by qtil via SLURM during job allocation.

Amazon Braket Rigetti: aws-braket (Rigetti)

Description: Executor on Rigetti hardware, provided by Amazon Web Services (AWS) Braket.

Provided by: Open-source Qristal SDK

Executes on: AWS (remote Rigetti QPU)

Parameters:

  • device: string, required. Set to Rigetti to use this backend.

  • format: string, required. The format of the circuit to be sent for execution. Must be either braket or openqasm3.

  • s3: string, required. The name of the AWS S3 bucket where the results of running the circuit should be saved. Must begin with "amazon-braket".

  • path: string, required. The path to the folder within the AWS S3 bucket where the results of running the circuit should be saved.

  • verbatim: boolean, optional, default false. Execute circuits verbatim as provided on AWS Braket. Setting verbatim = true causes the circuit submitted to Braket to be executed directly, without any optimisation, placement, transpilation or other IR transformations.

These parameters are set under the aws-braket heading in the remote_backends.yaml configuration file. To use an alternative file, assign its path to the qristal.session.remote_backend_database_path attribute.

Example: tests/AWSBraketHostedTester.Simple

Notes: The example in tests/AWSBraketHostedTester.Simple has the call to the Rigetti backend commented out at present, as no Rigetti devices were available on AWS Braket at the time of writing.

State-vector simulators

Quantum Brilliance CPU state vector: qb-statevector-cpu

Description: A noise-aware, state-vector simulator developed by Quantum Brilliance, built atop the Google Cirq qsim simulator.

Provided by: Qristal Emulator

Executes on: CPU

Parameters:

  • noise: boolean, must be set true. Include noise in the circuit simulation.

These parameters are currently qristal.core.session attributes.

Example: qb_statevector_noisy.py

Quantum Brilliance GPU state vector: qb-statevector-gpu

Description: A noise-aware, GPU-enabled state-vector simulator developed by Quantum Brilliance, built atop the Google Cirq qsim simulator.

Provided by: Qristal Emulator

Executes on: GPU

Parameters:

  • noise: boolean, must be set true. Include noise in the circuit simulation.

  • gpu_device_ids: Vector of integers, optional. Device IDs of GPUs to run on.

These parameters are currently qristal.core.session attributes.

Example: qb_statevector_noisy.py

Qsim state vector: qsim

Description: The Google Cirq qsim simulator.

Provided by: Open-source Qristal SDK

Executes on: CPU

Parameters: None

Example: multiplication.py

Microsoft sparse state vector: sparse-sim

Description: The Microsoft Quantum sparse state-vector simulator allows a high number of qubits to be simulated whenever the quantum circuit being executed preserves sparsity. It utilises a sparse representation of the state vector and methods to delay the application of some gates (e.g. Hadamard).

Provided by: Open-source Qristal SDK

Executes on: CPU

Parameters: None

Example: parametrization_demo.py

Quantum++ state-vector simulator: qpp and cudaq:qpp

Description: The Quantum++ state vector simulator, configured to use XACC IR (qpp) or QIR (cudaq:qpp).

Provided by: Open-source Qristal SDK

Executes on: CPU

Requires: CUDA Quantum (cudaq:qpp version only)

Parameters:

  • get_state_vec: boolean, optional. Retrieve final state-vector if set as true (default = false).

  • get_state_vec_raw: pointer of vector of complex double, optional. Holds the final state-vector.

These parameters are currently qristal.core.session attributes.

Example: demo1.py

cuQuantum state-vector simulators: cudaq:custatevec_fp32 and cudaq:custatevec_fp64

Description: Single (cudaq:custatevec_fp32) and double-precision (cudaq:custatevec_fp64) versions of the CUDA Quantum state vector simulator, built on CuQuantum libraries.

Provided by: Open-source Qristal SDK

Executes on: GPU

Requires: CUDA Quantum

Example: cudaq_qft.py

Aer state vector: aer (statevector)

Description: IBM Qiskit Aer noise-aware state-vector simulator.

Provided by: Open-source Qristal SDK

Executes on: CPU

Parameters:

  • aer_omp_threads integer, optional. The number of OpenMP threads that the AER simulator should run with. If not set, the environment variable OMP_NUM_THREADS is read and explicitly passed to AER instead, overriding any other choices of thread number done internally in AER. If neither is set, AER chooses the number of threads internally.

  • aer_sim_type: string, optional. The type of AER simulator. Can be set as aer_sim_type = statevector (default).

  • noise: boolean, optional. Include noise in the circuit simulation.

  • get_state_vec: boolean, optional. Retrieve final state-vector if set as true (default = false).

  • get_state_vec_raw: pointer of vector of complex double, optional. Holds the final state-vector.

These parameters are currently qristal.core.session attributes.

Example: noise_model.py

Amazon Braket SV1: aws-braket (SV1)

Description: State-vector simulator provided by Amazon Web Services (AWS) Braket.

Provided by: Open-source Qristal SDK

Executes on: AWS (remote CPU virtual machine)

Parameters:

  • device: string, required. Set to SV1 to use this backend.

  • format: string, required. The format of the circuit to be sent for execution. Must be either braket or openqasm3.

  • s3: string, required. The name of the AWS S3 bucket where the results of running the circuit should be saved. Must begin with "amazon-braket".

  • path: string, required. The path to the folder within the AWS S3 bucket where the results of running the circuit should be saved.

  • noise: boolean, required. Include noise in the circuit simulation.

  • verbatim: boolean, optional, default false. Execute circuits verbatim as provided on AWS Braket. Setting verbatim = true causes the circuit submitted to Braket to be executed directly, without any optimisation, placement, transpilation or other IR transformations.

These parameters are set under the aws-braket heading in the remote_backends.yaml configuration file. To use an alternative file, assign its path to the qristal.session.remote_backend_database_path attribute.

Example: tests/AWSBraketHostedTester.Simple

Notes: Up to 34 qubits and 10,000 shots supported.

Tensor network simulators

Quantum Brilliance Matrix-Product State (MPS): qb-mps and cudaq:qb_mps

Description: Quantum Brilliance’s noise-aware MPS simulator, configured to use XACC IR (qb-mps) or QIR (cudaq:qb_mps). The MPS method represents the quantum wavefunction as a tensor contraction of individual qubit’s quantum state. Each qubit’s quantum state is a rank-3 tensor (rank-2 tensor for boundary qubits).

Provided by: Qristal Emulator

Executes on: GPU

Requires: CUDA Quantum (cudaq:qb_mps version only)

Parameters:

  • max_bond_dimension: integer, optional, range: [1, 50000], default: 256. Maximum number of singular values kept in the virtual index/dimension.

  • initial_bond_dimension: integer, optional, range: [1, 50000], default: 1. Initial number of singular values in the virtual index/dimension. Can be used to speed up simulation if final state’s bond dimension is known.

  • svd_cutoff: floating-point, optional, default: 1.0e-8. Smallest absolute value of the singular values to keep.

  • rel_svd_cutoff: floating-point, optional, default: 1.0e-4. Smallest singular value, relative to the largest singular value, to keep.

  • noise: boolean, optional. Include noise in the circuit simulation.

  • measure_sample_method: string, optional. Measurement sampling modes: sequential for sequential cutensor-based sampling, cutensornet for single-shot cutensornet-based sampling, cutensornet_multishot for multi-shot cutensornet-based sampling, auto (default) for single-shot cutensornet-based sampling with cutensor-based sampling as fallback.

  • gpu_device_ids: Vector of integers. GPU device IDs. Note that the cudaq:qb_mps version currently only supports execution on a single GPU.

These parameters are currently qristal.core.session attributes.

Example: qb_mps_noisy.py

Quantum Brilliance Matrix-Product Density Operator: qb-mpdo and cudaq:qb_mpdo

Description: Quantum Brilliance’s noise-aware matrix-product density operator (MPDO) simulator, configured to use XACC IR (qb-mpdo) or QIR (cudaq:qb_mpdo). The MPDO method represents the density matrix as a tensor contraction of individual qubit’s density operator. Each qubit’s density operator is a rank-4 tensor (rank-3 tensor for boundary qubits).

Provided by: Qristal Emulator

Executes on: GPU

Requires: CUDA Quantum (cudaq:qb_mpdo version only)

Parameters:

  • max_bond_dimension: integer, optional, range: [1, 50000], default: 256. Maximum number of singular values kept in the virtual index/dimension.

  • initial_bond_dimension: integer, optional, range: [1, 50000], default: 1. Initial number of singular values in the virtual index/dimension. Can be used to speed up simulation if final state’s bond dimension is known.

  • svd_cutoff: floating-point, optional, default: 1.0e-8. Smallest absolute value of the singular values to keep.

  • rel_svd_cutoff: floating-point, optional, default: 1.0e-4. Smallest singular value, relative to the largest singular value, to keep.

  • noise: boolean, optional. Include noise in the circuit simulation.

  • measure_sample_method: string, optional. Measurement sampling modes: sequential for sequential cutensor-based sampling, cutensornet for single-shot cutensornet-based sampling, auto (default) for single-shot cutensornet-based sampling with cutensor-based sampling as fallback.

  • gpu_device_ids: Vector of integers. GPU device IDs. Note that the cudaq:qb_mpdo version currently only supports execution on a single GPU.

These parameters are currently qristal.core.session attributes.

Example: qb_mpdo_noisy.py

Quantum Brilliance purification: qb-purification and cudaq:qb_purification

Description: Quantum Brilliance’s noise-aware state purification simulator, configured to use XACC IR (qb-purification) or QIR (cudaq:qb_purification). The purification method represents the purified quantum state as a tensor contraction of individual qubit’s purified state. Each qubit’s purified state is a rank-4 tensor (rank-3 tensor for boundary qubits).

Provided by: Qristal Emulator

Executes on: GPU

Requires: CUDA Quantum (cudaq:purification version only)

Parameters:

  • max_bond_dimension: integer, optional, range: [1, 50000], default: 256. Maximum number of singular values kept in the virtual index/dimension.

  • initial_bond_dimension: integer, optional, range: [1, 50000], default: 1. Initial number of singular values in the virtual index/dimension. Can be used to speed up simulation if final state’s bond dimension is known.

  • max_kraus_dimension: integer, optional, range: [1, 50000], default: 256. Maximum number of singular values kept in the Kraus index/dimension.

  • initial_kraus_dimension: integer, optional, range: [1, 50000], default: 1. Initial number of singular values in the Kraus index/dimension (purification only). Can be used to speed up simulation if final state’s Kraus dimension is known.

  • svd_cutoff: floating-point, optional, default: 1.0e-8. Smallest absolute value of the singular values to keep.

  • rel_svd_cutoff: floating-point, optional, default: 1.0e-4. Smallest singular value, relative to the largest singular value, to keep.

  • noise: boolean, optional. Include noise in the circuit simulation.

  • measure_sample_method: string, optional. Measurement sampling modes: sequential for sequential cutensor-based sampling, cutensornet for single-shot cutensornet-based sampling, cutensornet_multishot for multi-shot cutensornet-based sampling, auto (default) for single-shot cutensornet-based sampling with cutensor-based sampling as fallback.

  • gpu_device_ids: Vector of integers. GPU device IDs. Note that the cudaq:purification version currently only supports execution on a single GPU.

These parameters are currently qristal.core.session attributes.

Example: qb_purification_noisy.py

TNQVM-ExaTN MPS: tnqvm

Description: Matrix product state simulator from the ExaTN package.

Provided by: Open-source Qristal SDK

Executes on: CPU

Parameters

  • max_bond_dimension:

  • svd_cutoff

These parameters are currently qristal.core.session attributes.

Example: qft.py

Aer MPS: aer (matrix_product_state)

Description: IBM Qiskit Aer noise-aware MPS simulator.

Provided by: Open-source Qristal SDK

Executes on: CPU

Parameters:

  • aer_omp_threads integer, optional. The number of OpenMP threads that the AER simulator should run with. If not set, the environment variable OMP_NUM_THREADS is read and explicitly passed to AER instead, overriding any other choices of thread number done internally in AER. If neither is set, AER chooses the number of threads internally.

  • aer_sim_type: string, required. The type of AER simulator. Must be set as aer_sim_type = matrix_product_state.

  • noise: boolean, optional. Include noise in the circuit simulation.

These parameters are currently qristal.core.session attributes.

Example: qft.py

Amazon Braket TN1: aws-braket (TN1)

Description: Tensor-network simulator provided by Amazon Web Services (AWS) Braket.

Provided by: Open-source Qristal SDK

Executes on: AWS (remote CPU virtual machine)

Parameters:

  • device: string, required. Set to TN1 to use this backend.

  • format: string, required. The format of the circuit to be sent for execution. Must be either braket or openqasm3.

  • s3: string, required. The name of the AWS S3 bucket where the results of running the circuit should be saved. Must begin with "amazon-braket".

  • path: string, required. The path to the folder within the AWS S3 bucket where the results of running the circuit should be saved.

  • noise: boolean, required. Include noise in the circuit simulation.

  • verbatim: boolean, optional, default false. Execute circuits verbatim as provided on AWS Braket. Setting verbatim = true causes the circuit submitted to Braket to be executed directly, without any optimisation, placement, transpilation or other IR transformations.

These parameters are set under the aws-braket heading in the remote_backends.yaml configuration file. To use an alternative file, assign its path to the qristal.session.remote_backend_database_path attribute.

Example: tests/AWSBraketHostedTester.Simple

Notes: Up to 48 qubits and 999 shots supported.

Density matrix simulators

CUDA Quantum density matrix simulator: cudaq:dm

Description: The CUDA Quantum density matrix simulator, built on CuQuantum libraries.

Provided by: Open-source Qristal SDK

Executes on: CPU

Requires: CUDA Quantum

Example: qft.py

Amazon Braket DM1: aws-braket (DM1)

Description: Density-matrix simulator provided by Amazon Web Services (AWS) Braket.

Provided by: Open-source Qristal SDK

Executes on: AWS (remote CPU virtual machine)

Parameters:

  • device: string, required. Set to DM1 to use this backend.

  • format: string, required. The format of the circuit to be sent for execution. Must be either braket or openqasm3.

  • s3: string, required. The name of the AWS S3 bucket where the results of running the circuit should be saved. Must begin with "amazon-braket".

  • path: string, required. The path to the folder within the AWS S3 bucket where the results of running the circuit should be saved.

  • noise: boolean, required. Include noise in the circuit simulation.

  • verbatim: boolean, optional, default false. Execute circuits verbatim as provided on AWS Braket. Setting verbatim = true causes the circuit submitted to Braket to be executed directly, without any optimisation, placement, transpilation or other IR transformations.

These parameters are set under the aws-braket heading in the remote_backends.yaml configuration file. To use an alternative file, assign its path to the qristal.session.remote_backend_database_path attribute.

Example: tests/AWSBraketHostedTester.Simple

Notes:

  • Up to 17 qubits and 10,000 shots supported.

  • Noise must be enabled in order to use this simulator. This is done by setting the qristal.core.session attribute noise = True.

Aer density matrix: aer (density_matrix)

Description: IBM Qiskit Aer noise-aware density matrix simulator.

Provided by: Open-source Qristal SDK

Executes on: CPU

Parameters:

  • aer_omp_threads integer, optional. The number of OpenMP threads that the AER simulator should run with. If not set, the environment variable OMP_NUM_THREADS is read and explicitly passed to AER instead, overriding any other choices of thread number done internally in AER. If neither is set, AER chooses the number of threads internally.

  • aer_sim_type: string, required. The type of AER simulator. Must be set as aer_sim_type = density_matrix.

  • noise: boolean, required. Include noise in the circuit simulation.

These parameters are currently qristal.core.session attributes.

Example: qft.py

Notes: Noise must be enabled in order to use this simulator. This is done by setting the qristal.core.session attribute noise = True.