Squeezing‐Enhanced Atom–Cavity Interaction in Coupled Cavities with High Dissipation Rates

Abstract

The realization of the strong coupling regime is requisite for implementing quantum information tasks. Here, a method for enhancing the atom-field coupling in highly dissipative coupled cavities is proposed. By introducing parametric squeezing into the primary cavity, which is only virtually excited under specific parametric conditions, coupling enhancement between the atom and the auxiliary cavity is realized for appropriate squeezing parameters. This enables the system to be robust against large cavity decay and atomic spontaneous emission. The observation of vacuum Rabi oscillations show that the originally weakly coupled system can be enhanced into an effective strong coupling regime. IntroductionCavity quantum electrodynamics (QED) studies the light-matter interactions between cavity photons and quantum emitters, [1] such as Rydberg and neutral atoms, [2][3][4] superconducting qubits, [5,6] and semiconductor quantum dots (QDs). [7][8][9] Strong coupling regime, where atom-cavity coupling strength has to be comparable or larger than atomic spontaneous emission rate γ and cavity decay rate κ, [10,11] is indispensable for experimentally investigating a manifold of quantum phenomena and implementing quantum information processing (QIP). [12] Such strong interaction often requires resonators with high quality (Q) factor and small mode volume (V ) simultaneously, which is still difficult to engineer in experiments. However, flexible configurations for the cavities shift the mutual constraint between high Q and small V . It is demonstrated that by employing a coupled cavity configuration, [13] the requirement for high Q and small V for one cavity can be removed, [14] hence, effective strong coupling in highly dissipative cavity QED system is realized. On the other hand, considerable efforts have been devoted to enhance the atom-cavity coupling strength. Parametric squeezing of the

Enhanced phonon blockade in a weakly-coupled hybrid system via mechanical parametric amplification

“…3, where one sees that g eff can be two orders of magnitude larger than g for a modest squeezing parameter r p = 3. It should be mentioned that the scheme proposed here is distinct from the exponential enhancement associated with the single-phonon (photon) spin-resonator interaction using mechanical (optical) parametric amplification [34,[67][68][69][70][71][72][73][74][75][76][77].…”

“…An effective strategy against this adverse effect is to use the squeezed-vacuum-reservoir technique, which has been studied extensively in recent reports [34,[67][68][69][70][71][72][73][74][75]77]. To be specific, by integrating an auxiliary, broadband microwave resonator to the original hybrid system, which acts as an engineered squeezed-vacuum reservoir, the squeezing-enhanced mechanical noise could be effectively suppressed, ensuring that the squeezed mechanical mode equivalently interacts with a thermal vacuum reservoir (see Appendix E for details).…”

“…As we mentioned in the main text, introducing MPA to enhance the spin-mechanical coupling also enhances the coupling between the mechanical mode and its bath environment, resulting in a significantly amplified mechanical noise. A promising strategy against this problem is to use the squeezed-vacuum-reservoir technique, which has been studied extensively in recent reports [67][68][69][70][71][72][73][74][75]77]. In what follows, we first sketch out the physical mechanism of the strategy and then show how to integrate it into our proposed device by engineering a microwave cavityoptomechanical system.…”

“…In particular, we introduce a periodic drive on the mechanical cantilever to implement the process of mechanical parametric amplification (MPA), which is inspired by a recent work for enhancing spin-phonon coupling [34]. By working in the squeezed frame, we show that our implementation enables an exponential coupling enhancement with respect to the bare spin-phonon coupling, which differs from the existing schemes based on MPA or optical parametric amplification [34,[67][68][69][70][71][72][73][74][75][76][77]. This offers a versatile platform for practical applications in solid-state systems where strong spin-mechanical coupling at the level of two phonons is within reach.…”

Noise-resistant phase gates with amplitude modulation

“…Considering two dominant channels of decoherence induced by the dissipation of the system: (i) Energy relaxations of excited state of the qutrits; (ii) Decay of the cavity mode. Note that as we introduce a parametric driving to squeeze the cavity mode for achieving the Rabi model, the squeezing also inputs thermal noise and two-photon correlation noise into the cavity [48][49][50][67][68][69]. This results in dissipative dynamics that have a similar form to thermal dissipation.…”