Room-temperature cavity quantum electrodynamics with strongly coupled Dicke states

Abstract

The strong coupling regime is essential for efficient transfer of excitations between states in different quantum systems on timescales shorter than their lifetimes. The coupling of single spins to microwave photons is very weak but can be enhanced by increasing the local density of states by reducing the magnetic mode volume of the cavity. In practice, it is difficult to achieve both small cavity mode volume and low cavity decay rate, so superconducting metals are often employed at cryogenic temperatures. For an ensembles of N spins, the spin-photon coupling can be enhanced by ffiffiffi ffi N p through collective spin excitations known as Dicke states. For sufficiently large N the collective spin-photon coupling can exceed both the spin decoherence and cavity decay rates, making the strong-coupling regime accessible. Here we demonstrate strong coupling and cavity quantum electrodynamics in a solid-state system at room-temperature. We generate an inverted spin-ensemble with N~1015 by photo-exciting pentacene molecules into spin-triplet states with spin dephasing time T Ã 2 $ 3 μs. When coupled to a 1.45 GHz TE 01δ mode supported by a high Purcell factor strontium titanate dielectric cavity (V m $ 0:25 cm 3 , Q~8,500), we observe Rabi oscillations in the microwave emission from collective Dicke states and a 1.8 MHz normal-mode splitting of the resultant collective spin-photon polariton. We also observe a cavity protection effect at the onset of the strong-coupling regime which decreases the polariton decay rate as the collective coupling increases. 1 and a key feature is the strong coupling regime, where excitations are coherently transferred between different quantum systems over timescales significantly shorter than their lifetimes. A striking example is the Dicke state,

Cavity-enhanced microwave readout of a solid-state spin sensor

“…Predictions of this model are consistent with measurements of the MW response of solid-state spin ensembles strongly coupled to dielectric resonators at room temperature 18,19 . Since the MW cavity magnetic field varies by only a small amount (≈±3.5%) over the diamond volume, we assume each spin has an identical coupling strength g s .…”

“…Our technique leverages strong collective coupling between a dielectric resonator cavity and a spin ensemble at room temperature. Similar coupled spin-cavity systems have recently been harnessed to demonstrate a roomtemperature maser 18 and Dicke superradiance 19,20 . Related cavity quantum electrodynamics (CQED) effects have also been employed for quantum information applications in cryogenic solid-state [21][22][23][24][25][26][27][28] and superconducting qubit [29][30][31] systems.…”

Growth, morphology and structure of mixed pentacene films

“…The concentration of pentacene has been reported to influence its applicability in optoelectronic applications. Previous literature has reported the use of an optically excited organic mixed molecular crystal for maser applications consisting of pentacene and pterphenyl, where pentacene is present in very low concentrations [8][9][10][11] . Conversely, pure pentacene has been implemented for devices such as organic field-effect transistors and organic photovoltaic devices.…”

Continuous-wave room-temperature diamond maser

“…For above-threshold maser oscillation the cooperativity needs to be greater than unity, C ≫ 1. The Purcell factor is key to enhancing maser performance [2,20] and contributes a factor g 2 s /κ c to the cooperativity. A high Purcell factor maser cavity was therefore designed and constructed using a hollow cylindrical single-crystal sapphire dielectric resonator (ε = 9.394, outer diameter 10 mm, inner diameter 5.1 mm and height 6.5 mm) housed centrally within an oxygen-free high-conductivity copper cavity (diameter 36 mm and height 18 mm).…”