Quantum tomography of entangled qubits by time-resolved single-photon counting with time-continuous measurements

TL;DR

This paper presents a novel framework for entanglement characterization of qubits using time-resolved single-photon counting with continuous measurements, incorporating realistic noise and timing uncertainties, and evaluates its effectiveness through numerical simulations.

Contribution

It introduces a new approach for quantum tomography based on time-continuous measurements in the time domain, applicable to photonic systems with realistic noise models.

Findings

Effective entanglement detection under timing uncertainty

High accuracy in quantum state reconstruction demonstrated

Framework applicable to polarization-entangled photon pairs

Abstract

In this article, we introduce a framework for entanglement characterization by time-resolved single-photon counting with measurement operators defined in the time domain. For a quantum system with unitary dynamics, we generate time-continuous measurements by shifting from the Schrodinger picture to the Heisenberg representation. In particular, we discuss this approach in reference to photonic tomography. To make the measurement scheme realistic, we impose timing uncertainty on photon counts along with the Poisson noise. Then, the framework is tested numerically on quantum tomography of qubits. Next, we investigate the accuracy of the model for polarization-entangled photon pairs. Entanglement detection and precision of state reconstruction are quantified by figures of merit and presented on graphs versus the amount of time uncertainty.