qasmsim

A QASM interpreter and quantum simulator in Rust.

Prerequisites

Make sure you have installed cargo. For compiling the WASM version, make sure you have wasm-pack also installed.

What is missing?

The interpreter golden path is almost complete, although the following is still lacking before version 1.0.0:

• [X] Add trigonometric and exponential functions in real expressions.
• [X] Create CLI interface.
  • [X] Better formatting of results.
  • [X] Add --shots option + histogram output.
• [X] Handle error paths.
  • [X] Improve error hierarchy.
  • [X] Add source references to errors.

And planned for 1.1.0 is:

• [ ] Allow including external source.
  • [ ] In the native lib.
  • [ ] In the WASM version.
• [ ] Add a semantic checker for checking the correctness of the program before runtime.
• [ ] Semantic comments for documenting the gates.

Although there is still no support for including external gate definitions, including qelib1.inc via the include instruction will work, for the qelib1.inc lib is embedded in the simulator:

include "qelib1.inc";

A sample QASM program can be found here:

qasm OPENQASM 2.0; include "qelib1.inc"; qreg q[2]; h q[0]; cx q[0], q[1];

The complete specification can be found under the QASM repository.

qasmsim CLI

Install qasmsim with:

sh $ cargo install --git https://github.com/delapuente/qasmsim

And simulate a QASM program with:

sh $ qasmsim source.qasm

See more options with:

``` $ qasmsim --help qasmsim 1.0.0 A QASM interpreter and quantum simulator in Rust.

USAGE: qasmsim [FLAGS] [OPTIONS] [source]

FLAGS: -b, --binary Prints the binary representation of the values -h, --help Prints help information -x, --hexadecimal Prints the hexadecimal representation of the values -i, --integer Prints the interger representation of the values. Default option --probabilities Prints the probabilities vector of the simulation. Ignored if shots is set --statevector Prints the state vector of the simulation. Ignored if shots is set -t, --times Prints times measured for parsing and simulating -V, --version Prints version information -v Verbosity of the output

OPTIONS: --out Output files prefix, print in the stdout if not present. The output format of each file is CSV. At most, three files are created with the names out.memory.csv, out.state.csv and out.times.csv --shots Specify the number of simulations

ARGS: QASM program file, read from stdin if not present ```

qasmsim library

qasmsim is also a library including a QASM parser which generates a QASM AST, an interpreter, and a quantum state-vector simulator. The command-line tool is just one of the multiple consumers the library can have. If you want to install the library functionality only, remove the default features when installing:

sh $ cargo install --no-default-features

Testing the project

You can refer to unit tests (in the files under the src folder) and integration tests (under the tests folder) to figure out what is implemented. For passing the tests of the project you can do:

sh $ cargo test

WASM version

qasmsim can be used in the web if you compile it for Web Assembly. Doing it is easy, simply download the sources, ensure you have wasm-pack installed and run:

sh $ wasm-pack build

It will compile your project and pack it inside the pkg folder. Now enter the www directory, install the dependencies with (you only need run this once):

sh $ npm install

And start the web server with:

sh $ npm start

Browse the URL provided by the second command and you'll see a blank page. Go to the developer tools of your browser and try running a small test:

js var result = qasmsim.run(` OPENQASM 2.0; include "qelib1.inc"; qreg q[2]; h q[0]; cx q[0], q[1]; `);

The module is exported by default as the qasmsim object in window and implments the following interface:

```ts interface qasmsim { run: (input: string, shots?: number) => Execution }

interface Execution { histogram?: Histogram, probabilities: Float64Array, statevector: Float64Array, memory: Memory, times: ExecutionTimes }

type Memory = { [key: string]: Array[number] } type Histogram = { [key: string]: Array[[number, number]] } type ExecutionTimes = { parsingtime: number, simulationtime: number, serialization_time: number } ```