A quantum computer state vector/stabilizer circuit simulator and assembly language
Project description
qsy
A quantum computer state vector/stabilizer circuit simulator and assembly language.
Table of Contents
Installation
$ pip install qsy
This will install the Python library qsy and command-line tool qsyasm.
qsy
qsy is a Python library for simulating quantum circuits.
Example
The following code creates an entangled state and prints its state vector in Dirac notation.
from qsy import QuantumRegister, gates
qr = QuantumRegister(2)
qr.apply_gate(gates.H, 0)
qr.apply_gate(gates.CX, 0, 1)
print(qr.to_dirac())
The output will be:
+0.70711|00> +0.70711|11>
qsyASM
qsyASM is a quantum assembly language acting as front-end for qsy. It allows
you to quickly write and debug quantum programs. It also allows for efficient
simulation of stabilizer circuits (a quantum circuit consisting solely of CNOT,
Hadamard, and phase gates) using the chp
back-end.
Usage
usage: qsyasm [-h] [-V] [-v] [-t] [-b B] [-s SHOTS] [--ignore-print-warning]
filename
qsyasm assembly runner
positional arguments:
filename qsyasm file to execute
optional arguments:
-h, --help show this help message and exit
-V, --version show program's version number and exit
-v, --verbose verbose output
-t, --time time program execution
-b B, --backend B simulator back-end to use: chp or statevector
(default: statevector)
-s SHOTS, --shots SHOTS
amount of shots to run
--ignore-print-warning
ignore register too large to print warning
Example
The following qsyASM program creates an entangled state and measures to a classical register:
qreg[2] q
creg[2] c
h q[0]
cx q[0], q[1]
meas q, c
Running it:
$ qsyasm examples/qsyasm/bell.qs
q[2]: +1|11>
+0 | 00
+0 | 01
+0 | 10
+1 | 11
c[2]: 11
Or running it a number of times:
$ qsyasm examples/qsyasm/bell.qs --shots=1024
q[2]: +1|00>
+1 | 00
+0 | 01
+0 | 10
+0 | 11
c[2]: {'11': 550, '00': 474}
More examples such as the quantum phase estimation algorithm can be found in the examples/qsyasm folder.
Syntax
The structure of a qsyASM program consists of a list of instructions. An instruction is defined as an operation followed by its arguments.
Operations
The instruction
cx q[0], q[1]
applies a CNOT operation with control qubit q[0]
and target qubit q[1]
.
Some operations take an angle (in radians) as argument. The parameterized operation
rz(pi/2) q[0]
rotates q[0]
π/2 radians around the Z axis. Expressions are allowed in
parameterized operations. Expression operators supported are +
, -
, *
, /
and **
(power). The variable pi
is available for convenience.
Adjoint Operation
To apply the adjoint of a gate, the adj
keyword is available. For example, to
apply the adjoint of S (S dagger):
adj s q[0]
List of Operations
Gate | qsyASM operation |
---|---|
Pauli I | i target |
Pauli X | x target |
Pauli Y | y target |
Pauli Z | z target |
Hadamard | h target |
S | s target |
T | t target |
Rx | rx(angle) target |
Ry | ry(angle) target |
Rz | rz(angle) target |
CNOT | cx control, target |
CZ | cz control, target |
CRx | crx(angle) control, target |
CRy | cry(angle) control, target |
CRz | crz(angle) control, target |
Toffoli | ccx controlA, controlB, target |
Note: The operations CNOT, H, S, X, Z and CZ can be efficiently simulated with the CHP back-end. Using any other operations with the CHP back-end will result in an error.
Registers
Defining a quantum register is done with the qreg
operation. The instruction
qreg[5] q
defines a 5 qubit quantum register named q
. Likewise, a classical register (useful for measuring) can be defined as
creg[5] c
Qubits in a quantum register are initiated to |0⟩, and bits in a classical register to 0.
Measurement
Measurement can be done on individual qubits, or a complete quantum state. The program
qreg[5] q
creg[1] c
h q[0]
meas q[0], c[0]
measures q[0]
to c[0]
, collapsing the state and storing the result in c[0]
. The measurement result can be ignored by only passing one argument to meas
:
meas q[0]
To measure a complete quantum state you can pass the whole quantum and classical register:
qreg[3] q
creg[3] c
; 3 qubit GHZ state
h q[0]
cx q[0], q[1]
cx q[0], q[2]
meas q, c
collapsing the quantum register q
and storing the measurement result in c
. This only works when the quantum register and classical register are equal in size.
License
This project is licensed under the MIT License. See the LICENSE file for the full license.
Project details
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