Statistical assertions for validating patterns and finding bugs in quantum programs

Abstract

In support of the growing interest in quantum computing experimentation, programmers need new tools to write quantum algorithms as program code. Compared to debugging classical programs, debugging quantum programs is difficult because programmers have limited ability to probe the internal states of quantum programs; those states are difficult to interpret even when observations exist; and programmers do not yet have guidelines for what to check for when building quantum programs. In this work, we present quantum program assertions based on statistical tests on classical observations. These allow programmers to decide if a quantum program state matches its expected value in one of classical, superposition, or entangled types of states. We extend an existing quantum programming language with the ability to specify quantum assertions, which our tool then checks in a quantum program simulator. We use these assertions to debug three benchmark quantum programs in factoring, search, and chemistry. We share what types of bugs are possible, and lay out a strategy for using quantum programming patterns to place assertions and prevent bugs.

Quantum Circuits for Dynamic Runtime Assertions in Quantum Computation

“…We conduct experiments on the quantum circuit simulator, QUIRK [1], to verify our mathematical derivation and an IBM Q (ibmqx4) quantum computer to check the effectiveness of the assertions in filtering errorneous results. The use of assertions for debugging harnesses is discussed in detail by Huang et al [3].…”

“…According to the previous work by Huang et al [3], 1 . In this paper, "classical states" refer to a state in the computational basis, |0⟩ and |1⟩, and measurements are assumed to be performed with respect three types of possible assertions are essential for debugging quantum programs: classical assertions, superposition assertions, and entanglement assertions.…”

“…The development of quantum programs remains a difficult task and debugging them is also very challenging. In the prior work, Huang et al [3] analyzed a set of quantum programs and identified that the three following types of assertions are needed in quantum programs: assertions for classical values, assertions for superposition states, and assertions for entangled states. They proposed the statistical approach to realize these assertions by measuring the qubits many times.…”

A lightweight approach to detect malicious/unexpected changes in the error rates of NISQ computers

“…Statistical [12] and dynamic [15,30] assertions can be inserted by the quantum programmer primarily for debugging purposes. These assertions are based on inserting checkpoints into the circuits, which require measurements at different stages of the design.…”

Full-state quantum circuit simulation by using data compression

“…As for quantum software development, several types of quantum applications require intermediate measurement [4,5,12,29]. In addition, recent studies focus on quantum software debugging by inserting assertions in the middle of quantum programs [34]. Tensor network simulation techniques do not effectively support intermediate measurement and full-state assertion checking for software debugging.…”