2020/02/29 by Bartosz Rzepkowski, Katarzyna Roszak
Chemistry · Computer Science · Physics and Astronomy · #Advanced NMR Techniques and Applications #Charge qubit #Dephasing #Flux qubit #Initialization #Phase qubit #Quantum Computing Algorithms and Architecture #Quantum Information and Cryptography #Quantum decoherence #Quantum entanglement #Qubit #Superposition principle #quant-ph
paper · pdf · doi:10.1007/s11128-020-02935-8
published as Quantum Inf Process 20, 1 (2021) · 12 pages, 3 figures
openalex created_date 2020/03/06 · arxiv created 2020/07/06 · openalex publication_date 2020/12/18 · arxiv updated 2021/02/23 · openalex updated_date 2026/08/05
Abstract We propose a scheme for the detection of qubit–environment entanglement which requires only operations and measurements on the qubit, all within reach of current experimental state-of-the-art. The scheme works for any type of interaction which leads to pure dephasing of the qubit as long as the initial qubit state is pure. The scheme is direct in the sense that it allows the detection of entanglement present in the system at time τ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>τ</mml:mi> </mml:math> after the initialization of the qubit in a superposition state. It requires a measurement on the qubit at time τ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>τ</mml:mi> </mml:math> and a comparison of the post-measurement evolution to the evolution obtained by a modified scheme. It becomes particularly simple when one of the qubit states is neutral with respect to the environment, such as in case of the most common choice of the NV center spin qubit or for excitonic charge qubits, when the environment is initially at thermal equilibrium. In this case, the post-measurement evolution needs to be compared only to the standard decoherence which is obtained without any qubit manipulation after the preparation of the initial state.