Quantum change point

Abstract

Sudden changes are ubiquitous in nature. Identifying them is of crucial importance for a number of applications in medicine, biology, geophysics, and social sciences. Here we investigate the problem in the quantum domain, considering a source that emits particles in a default state, until a point where it switches to another state. Given a sequence of particles emitted by the source, the problem is to find out where the change occurred. For large sequences, we obtain an analytical expression for the maximum probability of correctly identifying the change point when joint measurements on the whole sequence are allowed. We also construct strategies that measure the particles individually and provide an online answer as soon as a new particle is emitted by the source. We show that these strategies substantially underperform the optimal strategy, indicating that quantum sudden changes, although happening locally, are better detected globally.

4+8 pages, published version. New results added, including a theorem applicable to general multihypothesis discrimination problems

References in corpus (6)

• The Quantum Chernoff Bound
• The quantum Chernoff bound as a measure of distinguishability between density matrices: application to qubit and Gaussian states
• Local discrimination of mixed states
• On the Optimality of Square Root Measurements in Quantum State Discrimination
• Generalized quantum state discrimination problems
• Changepoint Problem in Quantumn Setting

Cited by in corpus (11)

• Quantum Machine Learning
• Quantum machine learning for quantum anomaly detection
• Deterministic realization of collective measurements via photonic quantum walks
• Vulnerability of quantum classification to adversarial perturbations
• Reconstruction of a Photonic Qubit State with Reinforcement Learning
• Duality games and operational duality relations
• Inductive supervised quantum learning
• Unsupervised classification of quantum data
• Online optimal exact identification of a quantum change point
• Identification of malfunctioning quantum devices
• Experimentally detecting a quantum change point via Bayesian inference