Simulator backends

QX quantum computer simulator

QX Simulator

Quantum Inspire offers a powerfull quantum computer simulator backend: QX.

QX Simulator is a quantum computer simulator that can simulate up to 37 qubits (on the Cartesius supercomputer) on a classical computer setup. It can execute quantum circuits and allows inspection of the simulated quantum state.

QX uses vector state representation of the qubit states. All qubits can be in full superposition and any arbitrary rotation can be applied to the qubits, thus supporting both Clifford gates and non-Clifford gates.

Simulator versions

Quantum Inspire offers three different instances of the QX Simulator. They vary in terms of turn-around time and available resources. They are hosted on succinct platforms:

QX single-node simulator

This version of QX runs on a commodity cloud-based server, with 4GB RAM. It has a fast turn-around time for simulations up to 26 qubits. For basic users, the commodity cloud-based server will be sufficient.

QX single-node simulator SurfSara

The SurfSara single-node QX Simulator instance uses the Knights Landing partition (knl) of SurfSara. With 96GB of memory, this allows simulation jobs of up to 31 qubits.

QX multi-node simulator SurfSara

The SurfSara multi-node QX Simulator instance will use 16 ‘fat’ nodes on Cartesius. This is the maximum amount of nodes that a single user can allocate. With 4TB of memory, this allows simulation jobs of up to 37 qubits.

Waiting time considerations

SurfSara supports the Dutch scientific community by providing advanced ICT infra-structure and hosts the Dutch national supercomputer Cartesius. QuTech is collaborating with SurfSara to make it possible to simulate more qubits. Because the supercomputer infra-structure is shared with the entire Dutch scientific community, simulations have to wait in line. The time a simulation has to wait depends on the amount of other users that want to use supercomputer resources, and can vary from minutes to hours.

For small jobs, this wait time will dominate the total turn-around time. For such jobs the commodity hardware instance (QX single-node simulator) is better suited. For larger jobs the wait time is offset by the faster execution time. For even larger jobs, the commodity hardware won’t run those jobs at all and the wait time is inevitable.

Waiting times on the QX single-node simulator SurfSara vary from minutes to hours, depending on overall usage patterns on the Cartesius supercomputer.

Waiting times on the QX multi-node simulator SurfSara vary from hours to days, depending on overall usage patterns on the Cartesius supercomputer. Only use this node if you really need the maximum amount of qubits.

Choosing a simulator instance depends largely on the amount of qubits that need to be simulated. Larger jobs require more resources. More resources means longer wait times to acquire the required resources.

Single-node commodity hardware

  • Waiting time: seconds to minutes
  • Maximum number of qubits: 26

Single-node SurfSara (Cartesius)

  • Waiting time: minutes to hours
  • Maximum number of qubits: 31

Multi-node SurfSara (Cartesius)

  • Waiting time: minutes to days
  • Maximum number of qubits: 37

Note that the waiting time is a combination of execution time and scheduling/queueing time.

More information

The following links provide more information about QX and cQASM, the Quantum Assembly Language that is used by QX: