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Simulator that computes final amplitudes of given bitstrings.
qsimcirq.QSimhSimulator(
qsimh_options: dict = {}
)
Used in the notebooks
Used in the tutorials 

Given a circuit and a list of bitstrings, computes the amplitudes of the given bitstrings in the state obtained by applying the circuit to the all zeros state. Implementors of this interface should implement the compute_amplitudes_sweep_iter method.
Args  

qsim_options

A map of circuit options for the simulator. These will be
applied to all circuits run using this simulator. Accepted keys and
their behavior are as follows:
See qsim/docs/usage.md for more details on these options. 
Methods
compute_amplitudes
compute_amplitudes(
program: 'cirq.AbstractCircuit',
bitstrings: Sequence[int],
param_resolver: 'cirq.ParamResolverOrSimilarType' = None,
qubit_order: 'cirq.QubitOrderOrList' = ops.QubitOrder.DEFAULT
) > Sequence[complex]
Computes the desired amplitudes.
The initial state is assumed to be the all zeros state.
Args  

program

The circuit to simulate. 
bitstrings

The bitstrings whose amplitudes are desired, input
as an integer array where each integer is formed from measured
qubit values according to qubit_order from most to least
significant qubit, i.e. in bigendian ordering.

param_resolver

Parameters to run with the program. 
qubit_order

Determines the canonical ordering of the qubits. This is often used in specifying the initial state, i.e. the ordering of the computational basis states. 
Returns  

List of amplitudes. 
compute_amplitudes_sweep
compute_amplitudes_sweep(
program: cirq.Circuit,
bitstrings: Sequence[int],
params: cirq.Sweepable,
qubit_order: cirq.QubitOrderOrList = cirq.QubitOrder.DEFAULT
) > Sequence[Sequence[complex]]
Wraps computed amplitudes in a list.
Prefer overriding compute_amplitudes_sweep_iter
.
compute_amplitudes_sweep_iter
compute_amplitudes_sweep_iter(
program: 'cirq.AbstractCircuit',
bitstrings: Sequence[int],
params: 'cirq.Sweepable',
qubit_order: 'cirq.QubitOrderOrList' = ops.QubitOrder.DEFAULT
) > Iterator[Sequence[complex]]
Computes the desired amplitudes.
The initial state is assumed to be the all zeros state.
Args  

program

The circuit to simulate. 
bitstrings

The bitstrings whose amplitudes are desired, input
as an integer array where each integer is formed from measured
qubit values according to qubit_order from most to least
significant qubit, i.e. in bigendian ordering.

params

Parameters to run with the program. 
qubit_order

Determines the canonical ordering of the qubits. This is often used in specifying the initial state, i.e. the ordering of the computational basis states. 
Returns  

An Iterator over lists of amplitudes. The outer dimension indexes the circuit parameters and the inner dimension indexes bitstrings. 
sample_from_amplitudes
sample_from_amplitudes(
circuit: 'cirq.AbstractCircuit',
param_resolver: 'cirq.ParamResolver',
seed: 'cirq.RANDOM_STATE_OR_SEED_LIKE',
repetitions: int = 1,
qubit_order: 'cirq.QubitOrderOrList' = ops.QubitOrder.DEFAULT
) > Dict[int, int]
Uses amplitude simulation to sample from the given circuit.
This implements the algorithm outlined by Bravyi, Gosset, and Liu in https://arxiv.org/abs/2112.08499 to more efficiently calculate samples given an amplitudebased simulator.
Simulators which also implement SimulatesSamples or SimulatesFullState
should prefer run()
or simulate()
, respectively, as this method
only accelerates sampling for amplitudebased simulators.
Args  

circuit

The circuit to simulate. 
param_resolver

Parameters to run with the program. 
seed

Random state to use as a seed. This must be provided manually  if the simulator has its own seed, it will not be used unless it is passed as this argument. 
repetitions

The number of repetitions to simulate. 
qubit_order

Determines the canonical ordering of the qubits. This is often used in specifying the initial state, i.e. the ordering of the computational basis states. 
Returns  

A dict of bitstrings sampled from the final state of circuit to
the number of occurrences of that bitstring.

Raises  

ValueError

if 'circuit' has nonunitary elements, as differences in behavior between sampling steps break this algorithm. 