THE PROCESS OF TRANSFORMING HIGH-LEVEL QUANTUM GATES INTO BASIS GATES FOR EXECUTION ON A REAL QUANTUM COMPUTER

Abstract

The article provides a systematic study of the process of transpilation of quantum algorithms, which is a mandatory stage of preparation for the execution of programs on real quantum devices. The essence of the concept of basic gates is disclosed as an elementary set of unitary operations that are supported by specific hardware. It is substantiated why high-level quantum gates (such as Hadamard, Toffoli, Fredkin) cannot be implemented directly on most modern quantum processors due to hardware limitations and architectural features, including the topology of connections between qubits.As an example, the IBM Quantum platform is considered, where the basic set for superconducting processors of the Eagle type includes RZ, SX, X gates and a two-qubit ECR (Echoed Cross Resonance) operation. A step-by-step analysis of the process of transpilation in the Qiskit environment has been carried out, which includes unification of the circuit, decomposition of high-level valves into basic ones, transformation of logical qubits into physical ones, consideration of the connection map, insertion of SWAP-valves, as well as optimization of the circuit to reduce its depth and the number of operations. It explains how the transpiler automatically adapts the logic quantum circuit to the limitations of the real device using built-in libraries of valve schedules and optimization passes (in particular, the SABRE algorithm). An example of transpilation of the circuit with valves H, CX and T is given, which shows the transition to a fully hardware-compatible implementation. The advantages of using different levels of optimization (0–3) of the Qiskit transpiler are determined, the influence of optimization on the accuracy of results and noise resistance is considered. Particular attention is paid to the issues of effective programming, considering hardware limitations: reducing the number of multi-qubit valves, rational use of auxiliary qubits, limiting the use of barriers and the feasibility of manually adjusting the correspondences of qubits in the scheme.