Quantum Circuits and Instructions

AbstractInstruction

Abstract super type for all the instrcutions.

An instruction applies one or more operations to a set of qubits and classical bits.

Methods

getqubit, getqubits, getbits, getbit inverse, opname, numqubits, numbits

See also

Instruction, Operation

Instruction(op, qtargets, ctargets) <: AbstractInstruction

Representation of an operation applied to specific qubit and bit targets.

Example

julia> Instruction(GateX(), (1,), ())
X @ q[1]

julia> Instruction(GateCX(), (1,2), ())
CX @ q[1], q[2]

julia> Instruction(Measure(), (3,), (3,))
Measure @ q[3], c[3]

See also

AbstractInstruction, Operation

Instruction(op, targets...)

Constructors an instruction from an operation and a list of targets.

By convention, if op is an N-qubit and M-bit operations, then the first N targets are used as qubits and the last M as bits.

Examples

julia> Instruction(GateX(), 1)
X @ q[1]

julia> Instruction(GateCX(), 1,2)
CX @ q[1], q[2]

julia> Instruction(Measure(), 3, 3)
Measure @ q[3], c[3]

getbit(instruction, i)

i-th target classical bit of an instruction.

Examples

julia> inst = Instruction(Measure(), 1, 3)
Measure @ q[1], c[3]

julia> getbit(inst, 1)
3

See also

getbits, getqubit, getqubits,

getbits(instruction)

Tuple of the classical bits which the instruction is applied to.

Examples

julia> inst = Instruction(Measure(), 1, 3)
Measure @ q[1], c[3]

julia> getbits(inst)
(3,)

See also

getbit, getqubits, getqubit

getqubit(instruction, i)

i-th target qubit of an instruction.

Examples

julia> inst = Instruction(GateCX(), 1, 3)
CX @ q[1], q[3]

julia> getqubit(inst, 2)
3

See also

getqubits, getbit, getbits

getqubits(instruction)

Tuple of quantum bits which the instruction is applied to.

julia> inst = Instruction(GateCX(), 1, 3)
CX @ q[1], q[3]

julia> getqubits(inst)
(1, 3)

See also

getqubit, getbits, getbit

Circuit([instructions])

Representation of a quantum circuit as a vector of instructions applied to the qubits.

The circuit can be initialized with an optional vector of instructions.

See OPERATIONS, GATES, or GENERALIZED for the list of operations to add to circuits.

Examples

Operation can be added one by one to a circuit with the push!(circuit, operation, targets...) function

julia> c = Circuit()
empty circuit


julia> push!(c, GateH(), 1)
1-qubit circuit with 1 instructions:
└── H @ q[1]

julia> push!(c, GateCX(), 1, 2)
2-qubit circuit with 2 instructions:
├── H @ q[1]
└── CX @ q[1], q[2]

julia> push!(c, GateRX(π / 4), 1)
2-qubit circuit with 3 instructions:
├── H @ q[1]
├── CX @ q[1], q[2]
└── RX(π/4) @ q[1]

julia> push!(c, Barrier(2), 1, 3)
3-qubit circuit with 4 instructions:
├── H @ q[1]
├── CX @ q[1], q[2]
├── RX(π/4) @ q[1]
└── Barrier @ q[1,3]

julia> push!(c, Measure(), 1, 1)
3-qubit circuit with 5 instructions:
├── H @ q[1]
├── CX @ q[1], q[2]
├── RX(π/4) @ q[1]
├── Barrier @ q[1,3]
└── Measure @ q[1], c[1]

Targets are not restricted to be single values, but also vectors. In this case a single push! will add multiple operations.

julia> push!(Circuit(), GateCCX(), 1, 2:4, 4:10)
6-qubit circuit with 3 instructions:
├── C₂X @ q[1:2], q[4]
├── C₂X @ q[1,3], q[5]
└── C₂X @ q[1,4], q[6]

is equivalent to

for (i, j) in zip(2:4, 4:10)
    push!(c, GateCX(), 1, i)
end

Notice how the range 4:10 is not fully used, since 2:4 is shorter.

Display

To display a a LaTeX representation of the circuit, we can just use Quantikz.jl

using Quantikz
c = Circuit()
...
displaycircuit(c)

or

savecircuit(c, "circuit.pdf")

depth(circuit)

Compute the depth of a quantum circuit.

The depth of a quantum circuit is a metric computing the maximum time (in units of quantum gates application) between the input and output of the circuit.

emplace!(circuit, operation, registers...)

Emplace an operation at the end of a circuit and applies it to the given registers.

julia> emplace!(Circuit(), control(3, GateSWAP()), [1,2,3], [4,5])
5-qubit circuit with 1 instructions:
└── C₃SWAP @ q[1:3], q[4:5]

julia> QFT()
lazy QFT(?)

julia> emplace!(Circuit(), QFT(), [1,2,3])
3-qubit circuit with 1 instructions:
└── QFT @ q[1:3]

draw(circuit)

Draw an ascii representation of a circuit.

NOTE it automatically detects the screen width and will split the circuit if it is too wide.