Output formats

--emit chooses what qirc writes, and -o writes it to a file. The command line reference lists every kind.

OpenQASM and QIR

--emit qasm3 writes OpenQASM 3 that keeps the program’s control flow: branches become if and else, loops a while over blocks, classical values typed variables and recorded values output variables. --emit qir writes QIR back out as LLVM IR in the profile the program needs, so qirc can sit between a QIR producer and any QIR consumer.

--emit qasm2 writes OpenQASM 2 with qelib1.inc gates for tools that only read that version. OpenQASM 2 has no else, loops or classical variables, so it covers straight line programs and a branch on one measurement to a block of gates, which becomes if(c1==1) x q[2]; with one single bit register per result, as teleportation needs. Anything else is refused with a pointer to --emit qasm3. Every corpus program that fits is accepted by Qiskit’s OpenQASM 2 parser and reads back into qirc with the same outcome probabilities.

Stim

--emit stim writes a Clifford program as a Stim circuit for error correction tools. Rotations by quarter turns become S, SQRT_X or SQRT_Y gates, measurements become M and resets R, and an X, Y or Z gate that depends on one measurement becomes feedback such as CX rec[-1] 2. Stim numbers measurements in the order they happen, so after routing the records can come in a different order from the result numbers. With --noisy and a calibration the circuit carries the same noise the simulator uses: DEPOLARIZE1 and DEPOLARIZE2 after each gate, M(p) for readout errors, X_ERROR after a reset, and PAULI_CHANNEL_1 for idle decoherence from T1 and T2. On 200 random programs, half with feedback and half with noise on examples/line5.cal, Stim’s samples match qirc’s to within 0.007 in total variation.

Circuit diagrams

--emit circuit prints an ASCII diagram, --emit quantikz writes a LaTeX quantikz environment and --emit svg a standalone SVG image. The two drawings pack each operation into the earliest column its qubits allow, write angles as fractions of pi where they are, and mark where each block of a branching program starts, as a \slice in LaTeX and a dashed line in SVG. The LaTeX needs \usetikzlibrary{quantikz2} and compiles with pdflatex.

$ qirc tests/corpus/base_profile_bell.ll --emit quantikz
\begin{quantikz}
\lstick{$q_{0}$} & \gate{H} & \ctrl{1} & \meter{} & \qw \\
\lstick{$q_{1}$} & \qw & \targ{} & \meter{} & \qw
\end{quantikz}