Pushing Purcell enhancement beyond its limits

Abstract

Purcell-enhanced emission from a coupled emitter-cavity system is a fundamental manifestation of cavity quantum electrodynamics (CQED). Starting from a theoretical description we derive a scheme for photon emission from an emitter coupled to a birefringent cavity that exceeds hitherto anticipated limitations. Based on a recent study and experimental investigation of the intra-cavity coupling of orthogonal polarisation modes in birefringent cavities [T. D. Barrett et al., Phys. Rev. Lett. 122, 083602 (2019)], we now decouple the emitter and the photon prior to emission from the cavity mode. Effectively, this is 'hiding' the emitter from the photon in the cavity to suppress re-excitation, increasing the overall emission through the cavity mirrors. In doing so we show that tailored cavity birefringence can offer significant advantages and that these are practically achievable within the bounds of present-day technology. It is found that birefringence can mitigate the tradeoff between stronger emitter-cavity coupling and efficient photon extraction. This allows for longer cavities to be constructed without a loss of performance -a significant result for applications where dielectric mirrors interfere with any trapping fields confining the emitter. We then generalise our model to consider a variety of equivalent schemes. For instance, detuning a pair of ground states in a threelevel emitter coupled to a cavity in a Λ-system is shown to provide the same enhancement, and it can be combined with a birefringent cavity to further increase performance. Additionally, it is found that when directly connecting multiple ground states of the emitter to form a chain of coupled states, the extraction efficiency approaches its fundamental upper limit. The principles proposed in this work can be applied in multiple ways to any emitter-cavity system, paving the way to surpassing the traditional limits of such systems with technologies that exist today. * thomas.barrett@physics.ox.ac.uk

Enhanced light–matter interaction in a hybrid photonic–plasmonic cavity

“…The single-atom cooperativity parameter of the dipole, C, coupled into the photonic cavity structure, could be obtained by the Purcell enhancement factor, F p [37], because it is directly proportional to the Purcell factor, which is calculated by the ratio of the fluorescence lifetimes of the off-resonant and on-resonant QDs with a particular optical mode.…”

Achievements and perspectives of optical fiber Fabry–Perot cavities

“…Recently, however, it was also shown that the birefringence of optical cavities can be turned into an advantage by making more field modes available for controlled lightmatter interaction [15,16], e.g for further enhancing the Purcell effect, see Sect. 3.1.…”

High quality-factor diamond-confined open microcavity

“…The reduction in lifetime results in a broadening of the homogeneous linewidth from ∆ν free = 1 2π γ 0 = 12.6 MHz to ∆ν ZPL cav = 1 2π [1 + ξ 0 (F P − 1)] γ 0 = 112 MHz, rendering the NV less sensitive to spectral wandering. Finally, we calculate the efficiency, η ZPL , of emitting a photon into the ZPL [44]; η ZPL = F P ξ0γ0 γcav = ξ0FP ξ0(FP−1)+1 = 89.0 % Alternatively, the NV-cavity coupling can be described with the Jaynes-Cummings Hamiltonian in terms of {g ZPL , κ, γ 0 }: where g ZPL = d NV E vac is the NVcavity coupling rate, κ is the cavity decay rate and γ 0 is, as before, the spontaneous emission rate [8,96].…”