import Command from 'projectq/src/ops/command.js'

public class | source

Command

Class used as a container to store commands. If a gate is applied to qubits, then the gate and qubits are saved in a command object. Qubits are copied into WeakQubitRefs in order to allow early deallocation (would be kept alive otherwise). WeakQubitRef qubits don't send deallocate gate when destructed.

Attributes: gate: The gate to execute qubits: Tuple of qubit lists (e.g. Quregs). Interchangeable qubits are stored in a unique order control_qubits: The Qureg of control qubits in a unique order engine: The engine (usually: MainEngine) tags: The list of tag objects associated with this command (e.g., ComputeTag, UncomputeTag, LoopTag, ...). tag objects need to support ==, != (eq and ne) for comparison as used in e.g. TagRemover. New tags should always be added to the end of the list. This means that if there are e.g. two LoopTags in a command, tag[0] is from the inner scope while tag[1] is from the other scope as the other scope receives the command after the inner scope LoopEngine and hence adds its LoopTag to the end. all_qubits: A tuple of control_qubits + qubits

Constructor Summary

Public Constructor
public	constructor(engine: BasicEngine, gate: BasicGate, qubits: Array<Qureg>, controls: Qureg \| Array<Qubit>, tags: any[])

Member Summary

Public Members
public get	allQubits: * Get all qubits (gate and control qubits).
public get	controlCount: *
public get	controlQubits: *
public set	controlQubits(nq: Qureg) Set control_qubits to qubits
public get	engine: *
public set	engine(ng: BasicEngine) Set / Change engine of all qubits to engine.
public	gate: *
public get	interchangeableQubitIndices: * Return nested list of qubit indices which are interchangeable.
public set	qubits
public get	qubits: *
public	tags: *

Private Members
private	_controlQubits: *
private	_engine: *
private	_qubits: *

Method Summary

Public Methods
public	addControlQubits(qubits: Array<Qubit>) Add (additional) control qubits to this command object.
public	apply() Apply a command.
public	copy(): Command return the copy of current command
public	equal(other: *): boolean
public	getInverse(): * Get the command object corresponding to the inverse of this command.
public	getMerged(other: Command): * Merge this command with another one and return the merged command object.
public	inspect(): string
public	orderQubits(qubits: Array<Qubit>): Array<Qubit> Order the given qubits according to their IDs (for unique comparison of commands).
public	toString(): string

Public Constructors

public constructor(engine: BasicEngine, gate: BasicGate, qubits: Array<Qureg>, controls: Qureg | Array<Qubit>, tags: any[]) source

Params:

Name	Type	Attribute	Description
engine	BasicEngine		engine which created the qubit (mostly the MainEngine)
gate	BasicGate		Gate to be executed
qubits	Array<Qureg>		Array of quantum registers (to which the gate is applied)
controls	Qureg \| Array<Qubit>		Qubits that condition the command.
tags	any[]		Tags associated with the command.

Public Members

public get allQubits: * source

Get all qubits (gate and control qubits).

Returns a tuple T where T[0] is a quantum register (a list of WeakQubitRef objects) containing the control qubits and T[1:] contains the quantum registers to which the gate is applied.

public get controlCount: * source

public get controlQubits: * source

public set controlQubits(nq: Qureg) source

Set control_qubits to qubits

public get engine: * source

public set engine(ng: BasicEngine) source

Set / Change engine of all qubits to engine.

public gate: * source

public get interchangeableQubitIndices: * source

Return nested list of qubit indices which are interchangeable.

Certain qubits can be interchanged (e.g., the qubit order for a Swap gate). To ensure that only those are sorted when determining the ordering (see _order_qubits), this.interchangeable_qubit_indices is used.

Example:

If we can interchange qubits 0,1 and qubits 3,4,5,
then this function returns [[0,1],[3,4,5]]

public set qubits source

public get qubits: * source

public tags: * source

Private Members

private _controlQubits: * source

private _engine: * source

private _qubits: * source

Public Methods

public addControlQubits(qubits: Array<Qubit>) source

Add (additional) control qubits to this command object.

They are sorted to ensure a canonical order. Also Qubit objects are converted to WeakQubitRef objects to allow garbage collection and thus early deallocation of qubits.

Params:

Name	Type	Attribute	Description
qubits	Array<Qubit>		List of qubits which control this gate, i.e., the gate is only executed if all qubits are in state 1.

public apply() source

Apply a command.

Extracts the qubits-owning (target) engine from the Command object and sends the Command to it.

public copy(): Command source

return the copy of current command

Return:

Command

public equal(other: *): boolean source

Params:

Name	Type	Attribute	Description
other	*

Return:

boolean

public getInverse(): * source

Get the command object corresponding to the inverse of this command. Inverts the gate (if possible) and creates a new command object from the result.

Return:

Throw:

NotInvertible

If the gate does not provide an inverse (see BasicGate.getInverse)

public getMerged(other: Command): * source

Merge this command with another one and return the merged command object.

Params:

Name	Type	Attribute	Description
other	Command		Other command to merge with this one (self)

Return:

Throw:

*	NotMergeable if the gates don't supply a get_merged()-function or can't be merged for other reasons.

public inspect(): string source

Return:

string

public orderQubits(qubits: Array<Qubit>): Array<Qubit> source

Order the given qubits according to their IDs (for unique comparison of commands).

Params:

Name	Type	Attribute	Description
qubits	Array<Qubit>		Array of quantum registers (i.e., tuple of lists of qubits)

Return:

Array<Qubit>

Ordered tuple of quantum registers

public toString(): string source

Return:

string