Solid-state room-temperature masers


Solid-state room-temperature masers

Wed, 19/01/2022 - 15:30 to 16:30
Dr Jonathan Breeze

Dr Jonathan Breeze from UCL will give a seminar title "Solid-state room-temperature masers". This talk will be present hybrid live/online, with venue details TBC. A bio and talk abstract are included below. If joining online, please use the Teams link provided.

The solid-state masers, invented in the 1950s, had a much less impressive career than its younger sibling the laser, mainly due to its dependence on cryogenic refrigeration and high-vacuum systems. Despite this, masers found niche application in deep-space communications and radio astronomy due to their unparalleled performance as low-noise amplifiers and oscillators. In 2012, the first room- temperature solid-state maser was demonstrated, exploiting an ensemble of inverted triplet states in photo-excited pentacene molecules doped into a p-terphenyl host [1]. Since then, this new class of maser has been miniaturized [2], characterized on nanosecond timescales [3] and shown to exhibit Rabi oscillations and normal-mode splitting, hallmarks of the strong-coupling regime of cavity quantum electrodynamics [4]. Unfortunately, the p-terphenyl host is volatile, has very poor thermal properties and unfavourable triplet sublevel decay rates – so that only pulsed operation lasting less than a millisecond has been observed to date. Alternative inorganic materials containing spin-polarizable defects such as diamond nitrogen-vacancy (NV) centres and [5,6] and vacancies in silicon carbide [7] have been proposed due to their slow spin-lattice relaxation and spin dephasing rates. These materials have the additional advantage of excellent thermal and mechanical properties.

In this seminar, I will discuss how the organic pentacene solid-state room-temperature maser came about, its subsequent development and how the quest for continuous operation naturally led towards diamond and nitrogen-vacancy centres. I will report on recent research into continuous-wave room-temperature masers based on optically pumped charged nitrogen-vacancy (NV) defect centres in diamond [8] and discuss prospects for macroscopically coherent quantum (Dicke) states and cavity quantum electrodynamics.

[1] M. Oxborrow, J. D. Breeze, N. Alford, Nature, 488, pp. 353–356 (2012)

[2] J. Breeze et al, Nature Communications, 6 (2015)
[3] E. Salvadori, J.D. Breeze et al, Scientific Reports, 7, 41836 (2017)
[4] J.D. Breeze et al, npj Quantum Information, 3, 40 (2017)
[5] J.H.N Loubser and J A van Wyk, Diamond Research, pp. 11-14, (1977)
[6] L. Jin et al, Nature Communications, 6 (2015)
[7] H. Kraus et al, Nature Physics, 10, pp. 157–162 (2014)
[8] J.D. Breeze et al, Nature, 555, pp. 493–496 (2018)


Jonathan studied Astrophysics at Leeds University, then worked at the National Physical Laboratory (NPL) in the Quantum Metrology division, before joining Matra-Marconi Space (now Airbus Space & Defence).

He returned to academia to do fundamental research into microwave dielectric ceramics, culminating in a PhD at London South Bank University on the theory and experiment of microwave absorption in single-crystal metal oxides.

He then moved to Imperial College London and in 2012, demonstrated a pulsed room-temperature maser using an optically-excited single-crystal of pentacene-doped para-terphenyl. Subsequent research led to the observation of strong-coupling in masers and the demonstration in 2018 of the first continuous-wave room-temperature s
olid-state maser using optically-pumped nitrogen-vacancy defects in diamond.

In 2019, he was awarded a Royal Society University Research Fellowship and received the Henry Moseley Medal by the Institute of Physics.

He joined the Department of Physics & Astronomy at UCL in 2021.