We study several extensions of the single-photon, cavity-mediated quantum logical gates recently proposed by Koshino, Ishizaka and Nakamura: to a double-sided cavity configuration, to the case where the two atomic ground states are nondegenerate, and to include nonadiabatic corrections. Our analysis can be used to estimate the effects of various imperfections, and to prepare the way for a proof-of-principle demonstration with present technology. An interesting result is that the leading correction to the adiabatic approximation can be made to vanish for a suitable choice of detunings, provided the cavity is "good enough" (high enough ratio of coupling to loss). This could significantly relax the need for long single-photon pulses.
A new analytic approach to investigate the zero-temperature time evolution of the Jaynes-Cummings system with cavity losses is developed. With the realistic coupling between the cavity and the environment assumed, a simple master equation is derived, leading to the explicit analytic solution for the resonant case. This solution is suitable for the analyses not only on the single excitation states but also on many excitation states, which enables us to investigate the photon coherent state and to observe sharp collapses and revivals under dissipation. For the off-resonant case, on the other han…
Resolved sideband cooling provides a crucial step in subrecoil cooling the trapped atoms toward their motional ground state, which is essential in atom-based quantum technologies. Here we present an enhanced dark-state sideband cooling in trapped atoms utilizing photon-mediated dipole-dipole interactions among them. By placing the atoms at the magic interparticle distances, we manifest an outperformed cooling behavior in the target atom, which surpasses the limit that a single atom permits. We further investigate various atomic configurations in a multiatom setup with a laser detuning and diff…
In this work we demonstrate theoretically how to use external laser field to control the population inversion of a single quantum dot exciton qubit in a nanocavity. We consider the Jaynes-Cummings model to describe the system, and the incoherent losses were take into account by using Lindblad operators. We have demonstrated how to prepare the initial state in a superposition of the exciton in the ground state and the cavity in a coherent state. The effects of exciton-cavity detuning, the laser-cavity detunings, the pulse area and losses over the qubit dynamics are analyzed. We also show how to…
We study the non-equilibrium dynamics of two coupled mechanical oscillators with general linear couplings to two uncorrelated thermal baths at temperatures $T_1$ and $T_2$, respectively. We obtain the complete solution of the Heisenberg-Langevin equations, which reveal a coherent mixing among the normal modes of the oscillators as a consequence of their off-diagonal couplings to the baths. Unique renormalization aspects resulting from this mixing are discussed. Diagonal and off-diagonal (coherence) correlation functions are obtained analytically in the case of strictly Ohmic baths with differe…
Non-Markovian delay-assisted sensing with waveguide-coupled quantum emitters
Wyant College of Optical Sciences, The University of Arizona（亚利桑那大学怀雅特光学学院）；Quantum, Photonics, and Computing Group, RTX BBN Technologies（RTX BBN科技公司量子、光子和计算组）；Department of Electrical and Computer Engineering, University of Maryland（马里兰大学电气与计算机工程系）；Department of Physics, The University of Arizona（亚利桑那大学物理系）
We characterize some of the distinctive hallmarks of magnon-magnon interaction mediated by the intracavity field of a microwave cavity, along with their testable ramifications. In general, we foreground two widely dissimilar parameter domains that bring forth the contrasting possibilities of level splitting and level crossing. The former is observed in the regime of strong magnon-photon couplings, particularly when the three modes bear comparable relaxation rates. This character is marked by the appearance of three distinguishable and non-converging polariton branches in the spectral response …
We analyze the requirements for fault-tolerant quantum computation with atom-atom gates based on cavity quantum electrodynamics (cQED) mediated by a photon with a finite pulse length. For short photon pulses, the distorted shape of the reflected pulses from the cQED system is a serious error source. We optimize the cQED system parameters to minimize the infidelity due to the shape distortion and the photon losses in a well-balanced manner for the fault-tolerant scheme using probabilistic gates [H. Goto and K. Ichimura, Phys. Rev. A 80, 040303(R) (2009)]. Our optimization greatly relaxes the re…
Achieving strong coupling between light and matter is usually a challenge in Cavity Quantum Electrodynamics (cQED), especially in solid state systems. For this reason is useful taking advantage of alternative approaches to reach this regime, and then, generate reliable quantum polaritons. In this work we study a system composed of a quantized single mode of a mechanical resonator interacting linearly with both a single mode nanocavity and a two-level single quantum dot. In particular, we focus on the behavior of the indirect light-matter interaction when the phonon mode interfaces both parts. …
Coherent control of an atomic collision in a cavity
根据S. B. Zheng和G. C. Guo（Phys. Rev. Lett. 85，2392（2000）），我们报道了一个实验，其中两个里德伯原子通过非共振腔的相干能量交换纠缠。该过程由微波光子的虚发射和吸收介导，其特征在于碰撞混合角比具有相同碰撞参量的自由空间中碰撞的原子大四个数量级。通过调节原子-腔的失谐量来控制最终的纠缠态。这一过程，基本上不敏感的热场和光子衰变，打开复杂的纠缠操纵有前途的前景。
Photon-mediated interactions between quantum emitters in engineered photonic baths is an emerging area of quantum optics. At the same time, non-Hermitian (NH) physics is currently thriving, spurred by the exciting possibility to access new physics in systems ruled by non-trivial NH Hamiltonians - in particular photonic lattices - which can challenge longstanding tenets such as the Bloch theory of bands. Here, we combine these two fields and study the exotic interaction between emitters mediated by the photonic modes of a lossy photonic lattice described by a NH Hamiltonian. We show in a paradi…
Enhanced quantum sensing mediated by a cavity in open systems
Argonne National Laboratory（阿贡国家实验室）；Infleqtion, Inc.（英弗莱克申公司）；University of Chicago（芝加哥大学）；IISER Thiruvananthapuram（印度科学教育与研究所特瓦拉纳普拉姆分校）；Center for Nanoscale Materials, Argonne National Laboratory（阿贡国家实验室纳米材料中心）
The beam-splitter (BS) is one of the most common and important components in modern optics, and lossless BS which features unitary transformation induces Hermitian evolution of light. However, the practical BS based on the conversion between different degree of freedoms are naturally non-Hermitian, as a result of essentially open quantum dynamics. In this work, we experimentally demonstrate a non-Hermitian BS for the interference between traveling photonic and localized magnonic modes. The non-Hermitian magnon-photon BS is achieved by the coherent and incoherent interaction mediated by the exc…
Semiconductor double quantum dot hybrid qubits are promising candidates for high-fidelity quantum computing. However, their performance is limited by charge noise, which is ubiquitous in solid-state devices, and phonon-induced dephasing. Here we explore methods for improving the quantum operations of a hybrid qubit, using strong microwave driving to enable gate operations that are much faster than decoherence processes. Using numerical simulations and a theoretical method based on a cumulant expansion, we analyze qubit dynamics in the presence of $1/f$ charge noise, which forms the dominant de…
