2022_05_20_Preparation of Entanglement States and Phase Space Perspective in 1D Waveguide QED System
Time:
May 20, 2022, 10:00 am (Taipei Time)
Speaker:
Kuan-Ting Lin
Title:
Preparation of Entanglement States and Phase Space Perspective for a Qubit Array in 1D Semi-infinite Waveguide QED Systems
Abstract:
The realization of the long-range quantum communication relies on the high efficiency quantum light-matter interface. One perspective of quantum information transfer from the flying qubits, photons, to stationary qubits is based on reversing the spontaneous emission process. The exponential decay profile of emission suggests the exponential rising single-photon pulse as possibly the best strategy to be absorbed by a single qubit. In many-qubit case, the temporal shape of the input pulse can be obtained via reversing the emission spectrum of cooperative, superand/or subradiant emission profile, where the effect of resonant dipole-dipole interaction and photon propagation time must be taken into account. The most efficient way to study the fidelity of preparation of a desired many-body entangled state is to analyze its atomic population. However, the readout of many-particle excited state is still impossible in the state-of-the-art experiments. Despite the fact that the loading efficiency can be obtained from the perspective of the conservation of energy, by which the energy of the output signal determines the efficiency, one can not know if the desired state is prepared. Hence, the witness on such an entangled many-body state is still lacking. In this work, we first study the two distant qubits coupled to a 1D terminated transmission line, where the dipole-dipole interaction must be time-delayed. We investigate preparation of an arbitrary two-qubit entangled state via a time-reversed photon by looking at the atomic population. In a case when the time-delayed effect can be neglected, we study the photon loading process from the perspective of the phase space, Wigner function, as the witness of state preparation. Furthermore, our method offers a way to calculate the real-time spectrum, which cannot be done by the master equation approach. The dephasing mechanism can also be included and has been studied.
Personal information:
Kuan-Ting Lin received his PhD from the Department of Physics, National Taiwan University in 2020, after which he went to the Physics Department, National Tsing Hua University for the postdoctoral researcher in Prof. Io-Chun Hoi's group from February to July, 2020. Then, he moved back to NTU to be postdoctoral research fellow in Prof. Guin-Dar Lin's group. His research interest is the many-particle quantum optical phenomena in 1D waveguide QED systems.
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