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arXiv:2108.11185 · Physical Review A

Unified generation and fast emission of arbitrary single-photon multimode W states

Jun‐Cong Zheng, Jie Peng, Pinghua Tang, Fei Li, Na Tan

Published Jun 3, 2022• 15 citations
arXivHTMLPDF

Abstract

We propose a unified and deterministic scheme to generate arbitrary single-photon multimode $W$ states in circuit QED. A three-level system (qutrit) is driven by a pump-laser pulse and coupled to $N$ spatially separated resonators. The coupling strength for each spatial mode ${g}_{i}$ totally decide the generated single-photon $N$-mode $W$ state $|{W}_{N}\ensuremath{\rangle}=\frac{1}{A}{\ensuremath{\sum}}_{i=1}^{N}{g}_{i}|{0}_{1}{0}_{2}\ensuremath{\cdots}{1}_{i}{0}_{i+1}\ensuremath{\cdots}{0}_{N}\ensuremath{\rangle}$, so arbitrary $|{W}_{N}\ensuremath{\rangle}$ can be generated inside resonators by adjusting ${g}_{i}$ and $N$. Moreover, such $W$ states can be fast emitted in symmetric temporal waveform with a probability reaching $98.9%$. The generation (or emission) time and fidelity can both be the same for arbitrary $|{W}_{N}\ensuremath{\rangle}$, independent of mode numbers. Finally, the time evolution process is easy to control since only the pump pulse is time-dependent.

DOI
10.1103/physreva.105.062408

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We investigate the efficiency of atom-cavity based photon-generation schemes to deliver single photons of arbitrary temporal shape. Our model applies to Raman transitions in three-level atoms with one branch of the transition driven by a laser pulse, and the other coupled to a cavity mode. For any possible shape of the single-photon wavepacket, we derive an unambiguous analytic expression for the shape of the required driving laser pulse. We furthermore discuss the constraints limiting the maximum probability for emitting any desired photon, and use these to estimate upper bounds for the efficiency of the process. The model is not only valid for Vacuum-Stimulated Raman Adiabatic Passages (V-STIRAP) in the strong-coupling and bad-cavity regime, but it generally allows controlling the coherence and population flow in any Raman process.
We present a scheme for generating entangled states of two qutrits, by using a 4-level system and a 3-level system coupled to a single cavity. Because of only employing resonant interactions, the entangled state can be fast created. This scheme is easy to implement in experiments since only a single cavity is needed and none of measurement, auxiliary system and identical system-cavity coupling constant is required. Furthermore, two-qutrit partially or maximally entangled states can be created by using this scheme. The proposal is quite general, which can be used to prepare entangled states of two qutrits in various physical systems, such as two natural or artificial atoms of the Λ-type or Δ-type three lowest levels, coupled to an optical or microwave cavity.