New paper with the Siddiqi group

Post date: Dec 17, 2016 3:04:01 AM

Our paper "Quantum Trajectories and Their Statistics for Remotely Entangled Quantum Bits" has been published by Physical Review X. This is APS's highly selective journal.

POPULAR SUMMARY:Of all of the predictions of quantum measurement theory, the ability to entangle by measurement is surely one of the most dramatic and exciting. This process can be thought of as dynamical and random given the continuous measurement of photons interacting with multiple spatially separated quantum systems. Many questions about the entanglement creation process are outstanding, such as the following: (i) What is the complete characterization of the dynamics of entanglement creation as a continuous trajectory? (ii) What is the statistical distribution of the entanglement at any time during the process? (iii) What is the most-likely way entanglement is created? Here, we provide systematic answers to these questions and others by analyzing experimentally entangled quantum trajectories of jointly measured superconducting quantum circuits.We track the quantum trajectories of two transmon qubits housed in separate superconducting cavities designed to minimize signal loss. We observe how the qubits evolve under joint continuous measurement by microwave frequency radiation, demonstrating a comprehensive understanding of dynamical entanglement generation by the measurement process. This entanglement generation is stochastic, and we present a detailed theoretical analysis of the statistics of the process, finding the full statistical distribution of created entanglement at any point during the process, as well as the most-likely paths in the quantum-state space to reach entangled states, and the associated times. In particular, we show that the two-qubit state collapses to one of three subspaces, and we determine the experimentally most-likely paths. We show excellent agreement between experimental data and our theory.

Our results present new ways to use joint measurement as a control mechanism to entangle remote systems for quantum information processing purposes.