Circuits

Circuit

A representation of a quantum circuit that contains the instructions to be performed on a quantum device and the requested result types.

See:

• Gates for all of the supported gates.
• Noises for all of the supported noise operations.
• Compiler Directives for all of the supported compiler directives.
• Results for all of the supported result types.

Circuit()

Construct an empty Circuit.

Circuit(m::Moments, ixs::Vector, rts::Vector{Result}, bri::Vector)

Construct a Circuit from a set of Moments, a vector of Instructions, a vector of Results, and a vector of basis rotation instructions.

Circuit(v)

Construct a Circuit from a Vector-like v containing tuples of:

• a Gate, Noise, or Result
• the target qubits on which to apply the operator
• any construction arguments to the operator, e.g. an angle or Observable

Examples

julia> v = [(H, collect(0:10)), (Rx, 1, 0.2), (BitFlip, 0, 0.1)];

julia> Circuit(v);

Qubit <: Integer

Wrapper struct representing a qubit.

Examples

julia> q = Qubit(0)
Qubit(0)

julia> q == 0
true

QubitSet

An OrderedSet-like object which represents the qubits a Circuit, Instruction, or Result acts on and their ordering. Elements may be Ints or Qubits.

Examples

julia> QubitSet(1, Qubit(0))
QubitSet with 2 elements:
  1
  Qubit(0)

julia> QubitSet([2, 1])
QubitSet with 2 elements:
  2
  1

julia> QubitSet()
QubitSet()

julia> QubitSet(QubitSet(5, 1))
QubitSet with 2 elements:
  5
  1

Operator

Abstract type representing operations that can be applied to a Circuit. Subtypes include Gate, Noise, Observable, and CompilerDirective.

QuantumOperator < Operator

Abstract type representing quantum operations that can be applied to a Circuit. Subtypes include Gate and Noise.

FreeParameter
FreeParameter(name::Symbol) -> FreeParameter

Struct representing a free parameter, which may be used to initialize to a parametrized Gate or Noise and then given a fixed value later by supplying a mapping to a Circuit.

depth(c::Circuit)

Returns the number of moments in c. Also known as the "parallel gate depth".

Examples

julia> c = Circuit();

julia> H(c, 0);

julia> CNot(c, 0, 1);

julia> depth(c)
2

qubits(c::Circuit) -> QubitSet

Returns a QubitSet containing all qubits that c is defined on.

Examples

julia> c = Circuit();

julia> H(c, 0);

julia> CNot(c, 0, 1);

julia> qubits(c)
QubitSet with 2 elements:
  0
  1

qubit_count(c::Circuit) -> Int

Returns the number of qubits that c is defined on.

Examples

julia> c = Circuit();

julia> H(c, 0);

julia> CNot(c, 0, 1);

julia> qubit_count(c)
2

measure(c::Circuit, target_qubits) -> Circuit

Add a Measure operator to c, ensuring only the targeted qubits are measured. A Measure operation can only be applied if the circuit does not contain any result types. If c has no qubits defined, or target_qubits are not within the qubit range of c, an ArgumentError is raised. If the circuit c contains any result types, or any of the target qubits are already measured, an ErrorException is raised.

Examples

julia> circ = Circuit([(H, 0), (CNot, 0, 1)]);

julia> circ = measure(circ, 0);

julia> circ.instructions
3-element Vector{Braket.Instruction}:
 Braket.Instruction{H}(H(), QubitSet(0))
 Braket.Instruction{CNot}(CNot(), QubitSet(0, 1))
 Braket.Instruction{Measure}(Measure(0), QubitSet(0))

julia> circ = Circuit([(H, 0), (CNot, 0, 1), (StateVector,)]);

julia> circ = measure(circ, 0);
ERROR: a circuit cannot contain both measure instructions and result types.
[...]

julia> circ = Circuit([(H, 0), (CNot, 0, 1)]);

julia> circ = measure(circ, [0, 1, 0]);
ERROR: cannot repeat qubit(s) in the same measurement.
[...]

Measure(index) <: QuantumOperator

Represents a measurement operation on targeted qubit, stored in the classical register at index.

Instruction
Instruction(o::Operator, target)

Represents a single operation applied to a Circuit. Contains an operator, which may be any subtype of Operator, and a target set of qubits to which the operator is applied.

Examples

julia> Braket.Instruction(H(), 1)
Braket.Instruction{H}(H(), QubitSet(1))

julia> Braket.Instruction(CNot(), [1, Qubit(4)])
Braket.Instruction{CNot}(CNot(), QubitSet(1, Qubit(4)))

julia> Braket.Instruction(StartVerbatimBox(), QubitSet())
Braket.Instruction{StartVerbatimBox}(StartVerbatimBox(), QubitSet())

ir(c::Circuit; serialization_properties::SerializationProperties=OpenQASMSerializationProperties())

Convert a Circuit into IR that can be consumed by the Amazon Braket service, whether local simulators, on-demand simulators, or QPUs. The IR format to convert to by default is controlled by the global variable IRType, which can be modified. Currently :JAQCD and :OpenQASM are supported for Circuits. If writing to OpenQASM IR, optional OpenQASMSerializationProperties may be specified.

ir(ahs::AnalogHamiltonianSimulation)

Generate IR from an AnalogHamiltonianSimulation which can be run on a neutral atom simulator or quantum device.

IRType

A Ref{Symbol} which records which IR output format to use by default. Currently, two formats are supported:

• :JAQCD, the Amazon Braket IR
• :OpenQASM, the OpenQASM3 representation

By default, IRType is initialized to use :OpenQASM, although this may change in the future. The current default value can be checked by calling IRType[]. To change the default IR format, set IRType[].

Examples

julia> IRType[]
:OpenQASM

julia> IRType[] = :JAQCD;

julia> IRType[]
:JAQCD

julia> IRType[] = :OpenQASM;

OpenQASMSerializationProperties(qubit_reference_type=VIRTUAL)

Contains information about how to serialize qubits when outputting to OpenQASM IR. The qubit_reference_type argument may be one of VIRTUAL or PHYSICAL.