Searcharxiv⌕ Search

arXiv subjects

Stefanie Muroya

Publications and source records attributed to Stefanie Muroya.

3 recordsLinked to original sources

Noise-aware Verification and Synthesis of Quantum Programs

While most research on quantum programming considers an idealized, noise-free semantics for quantum programs, we reason about quantum programs that are executed on real, noisy hardware. We consider the error models published by quantum hardware vendors to give a hardware-dependent semantics to quantum programs. This work presents a comprehensive study of noise-aware quantum programming, ranging from logical foundations to automated verification and synthesis. We develop a noise-aware quantum Hoare logic, and use it to derive algorithmic methods for the bounded verification of quantum programs on specific hardware, and for the automatic synthesis of noise-optimal loop-free quantum programs. In this way, we synthesize hardware-dependent subroutines that commonly occur in quantum algorithms, such as parity checks, quantum state preparation, and quantum state discrimination. We evaluate our method on the hardware specifications provided by the IBM Qiskit toolkit. Besides finding different optimal subroutines for different noise models, our synthesis tool also shows that classical probabilistic branching is needed for optimality in quantum programming.

cs.PL↗

Formal Verification of Continuous-Variable Quantum Programs

We provide a formal framework for Continuous-Variable Quantum Computing (CQC). While CQC is supported by photonic quantum hardware, we are not aware of a formal semantics for continuous-variable quantum programs nor of a unary Hoare logic for their verification. There are several technical obstacles to extending to CQC any of the formal frameworks available for Discrete-Variable Quantum Computing (DQC). Most importantly, continuous-variable quantum programs act on {\em infinite-dimensional} Hilbert spaces; their measurement outcomes are often {\em unbounded} and have expected values that are defined by an improper integral (or an infinite series), which may not converge. We overcome these challenges to give a formal semantics to a universal programming language for CQC and to provide the first Hoare logic for CQC. The assertions of our logic are built from polynomials over canonical observables. Besides proving relative completeness, we implement a symbolic weakest-precondition calculator for CQC based on our logic. Our tool has successfully verified CQC algorithms from textbooks and calculated their approximation errors for physically realizable implementations, proved the correctness (i.e., equivalence) of gate decompositions for CQC hardware, and computed the resource requirements (i.e., number of photon-number states) for achieving a desired accuracy in the classical simulation of continuous-variable quantum programs.

quant-ph↗

Multi-Environment POMDPs with Finite-Horizon Objectives

Partially Observable Markov Decision Processes (POMDPs) are systems in which one agent interacts with a stochastic environment, and receives only partial information about the current state. In a multi-environment POMDP (MEPOMDP), the initial state is unknown, and assumed to be adversarially chosen. In this work we focus on computing the optimal value and policy in MEPOMDPs with finite-horizon objectives. That problem is known to be PSPACE-complete in POMDPs. Our main results are as follows: (1) we establish that it is also PSPACE-complete in the more general setting of MEPOMDPs; (2) we present a practical algorithm and evaluate it on classical benchmarks, significantly outperforming the only previously known algorithm.

cs.AI↗