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OpenQASM in MIMIQ-CIRC#

The remote MIMIQ-CIRC services can can readily process and execute OpenQASM files, thanks to fast and feature-complete Julia and C++ parsers and interpreters.

Here is a simple comprehensive example of executing a QASM file on MIMIQ.

from mimiqcircuits import *
import matplotlib.pyplot as plt

conn = MimiqConnection().connect()

qasm = """
// Implementation of Deutsch algorithm with two qubits for f(x)=x
// taken from https://github.com/pnnl/QASMBench/blob/master/small/deutsch_n2/deutsch_n2.qasm
OPENQASM 2.0;

include "qelib1.inc";

qreg q[2];
creg c[2];

x q[1];
h q[0];
h q[1];
cx q[0],q[1];
h q[0];

measure q[0] -> c[0];
measure q[1] -> c[1];
"""

# Write the OPENQASM as a file
with open("/tmp/deutsch_n2.qasm", "w") as file:
    file.write(qasm)

# actual execution of the QASM file
job = conn.execute("/tmp/deutsch_n2.qasm"; algorithm="statevector")
res = conn.get_results(job)

plt.plot(res)

For more informations, read the documentation of executeqasm().

Behaviour of include files#

A common file used by many QASM files is the qelib1.inc file. This file is not defined as being part of OpenQASM 2.0, but its usage is so widespread that it might be considered as de-facto part of the specifications.

Note

We remind the careful reader that OpenQASM 2.0 specifications only define 6 operations: U,`CX`, measure, reset, barrier and if.

If we would parse every file together with qelib1.inc, we would have at the end just a list of simple U and CX gates, leaving behind any speed improvement that we would gain by using more complex gates as a block. For this reason, if you do not provide us explicitly the include files, we would not parse the common qelib1.inc but a simplified version of it, where almost all gate definitions are replaced by opaque definitions. These opaque definitions will be converted to the corresponding MIMIQ-CIRC gates listed in GATES().

Another alternative is to use the mimiqlib.inc directly in your file. For now is almost a copy of the modified qelib1.inc but in the future it will be extended to contain more gates and operations, diverging from qelib1.inc.

Relations between OpenQASM registers and MIMIQ indices#

During the parsing of the QASM file, we will assign a unique index to each qubit and classical bit. This index will be used to identify the qubit or bit in the MIMIQ-CIRC service.

The indices are assigned in the following way:

  • The first qubit is assigned index 1 (Julia), the second 2, and so on.

  • All registers retain the same ordering as in the QASM file.

  • Qubits and classical bits behave similarly but have they have each other its own sequence from indices, starting from 1.

A simple example will clarify this behaviour:

OPENQASM 2.0;
qreg q[2];
creg m[10];
qreg a[10];
creg g[2];

Will be parsed as:

QASM name

MIMIQ Qubit index

MIMIQ Bit index

q[0]

0

q[1]

1

a[0]

2

a[1]

3

a[9]

11

m[0]

0

m[1]

1

m[9]

0

g[0]

10

g[1]

11