import {CircuitDrawer} from 'projectq/src/backends/circuits/drawer.js'

public class | source

CircuitDrawer

Extends:

src/cengines.js~BasicEngine → CircuitDrawer

CircuitDrawer is a compiler engine which generates TikZ code for drawing quantum circuits.

The circuit can be modified by editing the settings.json file which is generated upon first execution. This includes adjusting the gate width, height, shadowing, line thickness, and many more options.

After initializing the CircuitDrawer, it can also be given the mapping from qubit IDs to wire location (via the :meth:set_qubit_locations function):

Example:


const circuit_backend = new CircuitDrawer()
circuit_backend.setQubitLocations({0: 1, 1: 0}) // swap lines 0 and 1
const eng = new MainEngine(circuit_backend)

... // run quantum algorithm on this main engine

console.log(circuit_backend.getLatex()) // prints LaTeX code

To see the qubit IDs in the generated circuit, simply set the `draw_id`
option in the settings.json file under "gates":"AllocateQubitGate" to
true:


"gates": {
"AllocateQubitGate": {
"draw_id": true,
"height": 0.15,
"width": 0.2,
"pre_offset": 0.1,
"offset": 0.1
},
...

The settings.json file has the following structure:


{
"control": { // settings for control "circle"
"shadow": false,
"size": 0.1
},
"gate_shadow": true, // enable/disable shadows for all gates
"gates": {
"GateClassString": {
GATE_PROPERTIES
}
"GateClassString2": {
...
},
"lines": { // settings for qubit lines
"double_classical": true, // draw double-lines for classical bits
"double_lines_sep": 0.04, // gap between the two lines for double lines
"init_quantum": true, // start out with quantum bits
"style": "very thin" // line style
}
}

All gates (except for the ones requiring special treatment) support the
following properties:


"GateClassString": {
"height": GATE_HEIGHT,
"width": GATE_WIDTH
"pre_offset": OFFSET_BEFORE_PLACEMENT,
"offset": OFFSET_AFTER_PLACEMENT,
},

Constructor Summary

Public Constructor
public	constructor(accept_input: boolean, default_measure: number)

Member Summary

Private Members
private	_accept_input: *
private	_default_measure: *
private	_free_lines: *[]
private	_map: {}
private	_qubit_lines: {}

Method Summary

Public Methods
public	getLatex(): string Return the latex document string representing the circuit.
public	isAvailable(cmd: Command): boolean Specialized implementation of isAvailable: Returns true if the CircuitDrawer is the last engine (since it can print any command).
public	printCMD(cmd: Command) Add the command cmd to the circuit diagram, taking care of potential measurements as specified in the init function.
public	receive(commandList: Command[]) Receive a list of commands from the previous engine, print the commands, and then send them on to the next engine.
public	setQubitLocations(idToLoc: Object) Sets the qubit lines to use for the qubits explicitly.

Public Constructors

public constructor(accept_input: boolean, default_measure: number) source

Params:

Name	Type	Attribute	Description
accept_input	boolean		If accept_input is true, the printer queries the user to input measurement results if the CircuitDrawer is the last engine. Otherwise, all measurements yield the result default_measure (0 or 1).
default_measure	number		Default value to use as measurement results if accept_input is false and there is no underlying backend to register real measurement results.

Private Members

private _accept_input: * source

private _default_measure: * source

private _free_lines: *[] source

private _map: {} source

private _qubit_lines: {} source

Public Methods

public getLatex(): string source

Return the latex document string representing the circuit.

Simply write this string into a tex-file or, alternatively, pipe the output directly to, e.g., pdflatex:

Return:

string

Example:


node my_circuit.js | pdflatex

where my_circuit.js calls this function and prints it to the terminal.

public isAvailable(cmd: Command): boolean source

Specialized implementation of isAvailable: Returns true if the CircuitDrawer is the last engine (since it can print any command).

Params:

Name	Type	Attribute	Description
cmd	Command		Command for which to check availability (all Commands can be printed).

Return:

boolean

true, unless the next engine cannot handle the Command (if there is a next engine).

public printCMD(cmd: Command) source

Add the command cmd to the circuit diagram, taking care of potential measurements as specified in the init function.

Queries the user for measurement input if a measurement command arrives if accept_input was set to true. Otherwise, it uses the default_measure parameter to register the measurement outcome.

Params:

Name	Type	Attribute	Description
cmd	Command		Command to add to the circuit diagram.

public receive(commandList: Command[]) source

Receive a list of commands from the previous engine, print the commands, and then send them on to the next engine.

Params:

Name	Type	Attribute	Description
commandList	Command[]		List of Commands to print (and potentially send on to the next engine).

public setQubitLocations(idToLoc: Object) source

Sets the qubit lines to use for the qubits explicitly.

To figure out the qubit IDs, simply use the setting draw_id in the settings file. It is located in "gates":"AllocateQubitGate". If draw_id is true, the qubit IDs are drawn in red.

Params:

Name	Type	Attribute	Description
idToLoc	Object		Dictionary mapping qubit ids to qubit line numbers.

Throw:

Error

If the mapping has already begun (this function needs be called before any gates have been received).