vqc_lite.circuit_stack_pennylane package

Submodules

vqc_lite.circuit_stack_pennylane.block module

class vqc_lite.circuit_stack_pennylane.block.Block_CNOT_P(pm1=0)

Bases: Block_P

This block consists of a Controlled-X gate, followed by 2 general single qubit unitaries (GU1), one on each qubit. It takes 6 parameters.

assemble()

Automatically called during initialization to generate the circuit function.

class vqc_lite.circuit_stack_pennylane.block.Block_CZ_P(pm1=0)

Bases: Block_P

This block consists of a Controlled-Z gate, followed by 2 general single qubit unitaries, one on each qubit. It takes 6 parameters.

assemble()

Automatically called during initialization to generate the circuit function.

class vqc_lite.circuit_stack_pennylane.block.Block_GU1_P(pm1=0)

Bases: Block_P

This block consists of only 1 general single qubit unitary. It’s takes 3 parameters.

assemble()

Automatically called during initialization to generate the circuit function.

class vqc_lite.circuit_stack_pennylane.block.Block_GU2_P

Bases: Block_P

This block consists of only 1 general two qubit unitary (GU2). It takes 15 parameters.

assemble()

Automatically called during initialization to generate the circuit function.

class vqc_lite.circuit_stack_pennylane.block.Block_P(pm1=0)

Bases: object

The Pennylane version of the circuit stack consists of 3 levels, which from bottom to top are: gate, block and circuit.

Note that because of functions such as “qml.MPS” and “qml.broadcast”, the arrangement of blocks could be easily handled at the circuit level for many common Ansätze. Thus, at the moment the “layer” level which exists in the other circuit stack is omitted here. However, when more complicated Ansätze come in the future, maybe it’s better to also introduce the layer here.

In the other stack where attributes are passed from one level to the next and only assembled and mapped to gate functions at the circuit level. In the Pennylane stack, in contrary, we directly pass callable gate functions called “circuit”.

A Block is the repeating unit in a layer. A block consists of >= 1 parmaterized or fixed gate(s).

Parameters

pm1 (int) – parametrization method for GU1

assemble()

Automatically called during initialization to generate the circuit function.

vqc_lite.circuit_stack_pennylane.circuit module

class vqc_lite.circuit_stack_pennylane.circuit.Circuit_P(nq=4, **kwargs)

Bases: object

The Pennylane version of the circuit stack consists of 3 levels, which from bottom to top are: gate, block and circuit.

Circuits are at the top level of the stack.

Some important attributes of a circuit include:

  1. nq: The number of qubits involved in the circuit.

  2. components: A list of circuits of the constituent layer(s).

  3. param_shape: The shape of parameters for each component.

  4. mq: “measure_qubits”. By default, it is False, meaning all qubits are measured and the exact output statevector will be returned. Else, it could be a list of the indices of the qubits to be measured. Then the probability distribution of bitstrings of the output qubits will be returned.

Parameters

  • nq (int) – the number of qubits

  • mq (list of integers or False) – the qubits to be measured

assemble()

Automatically called during initialization to generate the circuit function.

get_distance_with(params, psi)

Compute the coordinate-wise distance between the output state of the VQC with parameter inputs and a target state psi.

Parameters

  • params ((jax) numpy array / list) – parameter inputs

  • psi ((jax) numpy array) – target state

get_fidelity_with(params, psi)

Compute the fidelity between the output state of the VQC with parameter inputs and a target state psi.

Parameters

  • params ((jax) numpy array / list) – parameter inputs

  • psi ((jax) numpy array) – target state

get_loss(params, psi, lf='td')

Applicable when mq is False.

Compute the “loss” of the output state of the VQC with parameter inputs compared to a target state psi.

Often called during optimization for state preparation. Could also be used for more general purposes.

Parameters

  • params ((jax) numpy array / list) – parameter inputs

  • psi ((jax) numpy array) – target state

  • lf (int) –

    choice of loss function, currently supports:

    1. coordinate-wise distance

    2. squared coordinate-wise distance

    3. 1 - fidelity

    4. trace distance

get_np()

Compute the total number of parameters in the block.

Return type

int

params_to_proper_shape(flattened_params)

Reshape a flattened array of parameters into the form ready to be fed into the circuit.

Parameters

flattened_params ((jax) numpy array / list of float) – flattened parameters

Returns

parameters reshaped according to param_shape

Return type

list of (jax) numpy arrays

plot(file_name=None, **kwargs)

Make a plot of the circuit and optionally save as a file.

Parameters

  • file_name (str) – The name of the file that saves the plot

  • fig_size (tuple of int) – size of the image

  • dpi (int) – quality of the image

run_with_param_input(params)

Run the full circuit with parameter inputs for the parametrized gates.

Parameters

params ((jax) numpy array / list) – parameter inputs

to_qasm(params, file_name)

Outputs the gate sequence with parameter inputs in OpenQASM format. May fail, depending on the type of gates involved.

Parameters

  • params ((jax) numpy array / list) – parameter inputs

  • file_name (str) – The name of the file that saves the plot

vqc_lite.circuit_stack_pennylane.circuit_mps module

class vqc_lite.circuit_stack_pennylane.circuit_mps.MPS_CNOT_P(nl=1, nq=11, irb=None, version=0, pm1=0, **kwargs)

Bases: MPS_P

MPS with CNOT blocks.

Parameters

pm1 (int) – parameterization method for GU1. See gate.py

class vqc_lite.circuit_stack_pennylane.circuit_mps.MPS_CZ_P(nl=1, nq=11, irb=None, version=0, pm1=0, **kwargs)

Bases: MPS_P

MPS with CZ blocks.

Parameters

pm1 (int) – parameterization method for GU1. See gate.py

class vqc_lite.circuit_stack_pennylane.circuit_mps.MPS_GU2_P(nl=1, nq=11, version=0, **kwargs)

Bases: MPS_P

MPS with GU2 blocks.

class vqc_lite.circuit_stack_pennylane.circuit_mps.MPS_P(block, nl=1, nq=11, irb=None, version=0, **kwargs)

Bases: Circuit_P

This is the basis class for all circuits inspired by matrix product states (MPS).

Parameters

  • block (Block_P) – The block object underlying the circuit.

  • nl (int) – The number of layers in the circuit.

  • nq (int) – The number of qubits in the circuit.

  • irb (Block) – The block object for initial rotation, if applicable. It’s None by default.

  • version (int) –

    define the block arrangement in:

    1. right canonical form

    2. right canonical form with periodic condition

    3. mixed canonical form

Module contents