The stability of optical cavity maser power

Yoh‐Han Pao

Wern Ng, Xiaotian Xu, Max Attwood +4 more

Masers can deliver ultralow-noise amplification of microwave signals in medical imaging and deep-space communication, with recent research being rekindled through the discovery of gain media operating at room-temperature, eschewing bulky cryogenics that hindered their use. This work shows the discovery of 6,13-diazapentacene doped in para-terphenyl (DAP:PTP) as a maser gain medium that can operate at room-temperature, without an external magnetic field. With a maser output power of -10 dBm, it is on par with pentacene-doped para-terphenyl in masing power, while possessing compelling advantages such as faster amplification startup times, being pumped by longer wavelength light at 620 nm and greater chemical stability from nitrogen groups. Furthermore, the maser bursts from DAP:PTP allow one to reach the strong coupling regime for cavity quantum electrodynamics, with a high cooperativity of 182. The optical and microwave spin dynamics of DAP:PTP are studied in order to evaluate its capabilities as a maser gain medium, where it features fast intersystem crossing and an advantageously higher triplet quantum yield. The results pave the way for the future discovery of similar maser materials and help designate them as promising candidates for quantum sensors, optoelectronic devices and the study of cavity quantum electrodynamic effects at room-temperature.

Bell Telephone Laboratories, Henry E. Breed

HERBERT WALTHER

Applications in quantum information and quantum cryptography require radiation sources capable of producing photons in a deterministic way. This paper reviews experiments using cavity quantum electrodynamics directed towards this aim and performed in our laboratory. Two methods will be described. One uses the one-atom maser, and the other, trapped ions in an optical cavity. In order to generate photons on demand, the one-atom maser operates under the condition of the so-called trapping states. In this situation the field of the micromaser stabilizes to photon number states. Thus, the quantum states of the radiation field become directly visible. Hence, the one-atom maser is the only experiment to show a spectrum of photon quantum states. In the second experiment, the strong localization and position control achievable in an ion trap is combined with an optical cavity in a cavity quantum electrodynamic experiment leading to a big step forward towards a deterministic photon source in the visible spectral region.

L. Jin, Matthias Pfender, Nabeel Aslam +4 more

The application of masers is limited by its demanding working conditions (high vacuum or low temperature). A room-temperature solid-state maser is highly desirable, but the lifetimes of emitters (electron spins) in solids at room temperature are usually too short (∼ns) for population inversion. Masing from pentacene spins in p-terphenyl crystals, which have a long spin lifetime (∼0.1 ms), has been demonstrated. This maser, however, operates only in the pulsed mode. Here we propose a room-temperature maser based on nitrogen-vacancy centres in diamond, which features the longest known solid-state spin lifetime (∼5 ms) at room temperature, high optical pumping efficiency (∼10(6) s(-1)) and material stability. Our numerical simulation demonstrates that a maser with a coherence time of approximately minutes is feasible under readily accessible conditions (cavity Q-factor ∼5 × 10(4), diamond size ∼3 × 3 × 0.5 mm(3) and pump power <10 W). A room-temperature diamond maser may facilitate a broad range of microwave technologies.