Glossary

vQPU
virtual QPU: A classical process running on an HPC environment with an allocated set of classical resources that simulates the behaviour of a real QPU. It is composed of a server (manages user–vQPU communication) and a simulator (performs the actual execution). See Virtual QPU.
QPU: In this documentation, the QPU Python object that represents a deployed vQPU and is used to submit quantum tasks to it. Also refers to real quantum hardware (e.g. CESGA’s QMIO), which can be deployed alongside vQPUs.
family: A name that identifies a group of vQPUs deployed together by a single qraise call. It is set with the --family flag (Bash) or the family argument (Python) and is later used to select (get_QPUs) or release (qdrop) that group. If not provided, it defaults to the SLURM job id of the deployment.
co-located mode: Deployment mode in which a vQPU can be accessed from any node, not only the one it was deployed on. Enabled with --co-located (Bash) / co_located=True (Python). The alternative is hpc mode.
hpc mode: Default deployment mode in which a vQPU can only be accessed from the node on which it was deployed. Contrast with co-located mode.
DQC
Distributed Quantum Computing: Computing paradigm in which a quantum computation is distributed across several QPUs. CUNQA emulates DQC architectures and supports three schemes: embarrassingly parallel, classical communications and quantum communications.
embarrassingly parallel: DQC scheme with no inter-QPU communication: independent quantum tasks are mapped to the available vQPUs. Also referred to as the no-communications (NC) scheme.
classical communications: DQC scheme (CC) in which vQPUs exchange classical bits (measurement outcomes) during execution to classically condition operations on remote qubits.
quantum communications: DQC scheme (QC) in which vQPUs share quantum entanglement via the teledata and telegate protocols.
data qubit: A computation qubit of a circuit, used to carry out the quantum algorithm.
communication qubit
comm qubit: A qubit reserved for inter-vQPU quantum communication (entanglement generation in teledata and telegate). Declared with the tuple form CunqaCircuit((num_data_qubits, num_comm_qubits), num_clbits).
teledata: Quantum-communication protocol that teleports the state of a data qubit from one circuit to another. Exposed through qsend / qrecv.
telegate: Quantum-communication protocol that shares a control qubit across vQPUs so that a remote controlled gate can be applied locally. Exposed through cat_entangler / cat_disentangler.
backend: The configuration describing the device a vQPU emulates (basis gates, coupling map, noise model, simulator, …). Provided as a JSON file through --backend / backend and represented in Python by Backend.
simulator: The software library that performs the quantum simulation inside a vQPU (e.g. Aer, Munich, Qulacs). Selected with --simulator; see Simulators.