Soft-clamped silicon nitride membrane resonators are capable of coherence times τ exceeding 100 ms at millikelvin bath temperatures. However, harnessing strong optomechanical coupling in dry dilution refrigerators remains a challenge due to vibration issues and heating by optical absorption. Here, we address these issues with an actuator-free optical cavity and mechanical resonator design, with the cavity mounted on a simple vibration-isolation platform. We observe dynamical backaction when the cavity is driven with a free-space optical beam stabilized close to the red sideband using a two-beam locking scheme. Finally, we characterize the effect of absorption heating on coherence time, finding it scales with the intracavity power P as τ ∝ P-(0.34±0.04).

Cavity electromechanics relies on parametric coupling between microwave and mechanical modes to manipulate the mechanical quantum state, and provide a coherent interface between different parts of hybrid quantum systems. High coherence of the mechanical mode is of key importance in such applications, in order to protect the quantum states it hosts from thermal decoherence. Here, we introduce an electromechanical system based around a soft-clamped mechanical resonator with an extremely high Q-factor (>10 9 ) held at very low (30 mK) temperatures. This ultracoherent mechanical resonator is capacitively coupled to a microwave mode, strong enough to enable ground-state-cooling of the mechanics ( n̅_min=0.76± 0.16 ). This paves the way towards exploiting the extremely long coherence times ( t coh > 100 ms) offered by such systems for quantum information processing and state conversion.

We present an implementation of a hybrid electro-optical quantum transducer made with an ultracoherent nanomembrane, whose motion is coupled to both an optical cavity and a microwave cavity. Interestingly, this membrane can be used as an embedded quantum memory, with an inferred coherence time of more than 100 ms.

Journal Article Laser-Based Phase Contrast for Transmission Electron Microscopy Get access O Schwartz, O Schwartz Department of Physics, University of California, Berkeley, CA, USALawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA, USA Search for other works by this author on: Oxford Academic Google Scholar J J Axelrod, J J Axelrod Department of Physics, University of California, Berkeley, CA, USALawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA, USA Search for other works by this author on: Oxford Academic Google Scholar S L Campbell, S L Campbell Department of Physics, University of California, Berkeley, CA, USALawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA, USA Search for other works by this author on: Oxford Academic Google Scholar C Turnbaugh, C Turnbaugh Department of Physics, University of California, Berkeley, CA, USALawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA, USA Search for other works by this author on: Oxford Academic Google Scholar A Herman, A Herman Department of Physics, University of California, Berkeley, CA, USALawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA, USA Search for other works by this author on: Oxford Academic Google Scholar E Planz, E Planz Department of Physics, University of California, Berkeley, CA, USALawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA, USA Search for other works by this author on: Oxford Academic Google Scholar R M Glaeser, R M Glaeser Department of Molecular and Cell Biology, University of California, Berkeley, CA, USALawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA, USA Search for other works by this author on: Oxford Academic Google Scholar H Müller H Müller Department of Physics, University of California, Berkeley, CA, USALawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA, USA Corresponding author: hm@berkeley.edu Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 25, Issue S2, 1 August 2019, Pages 982–983, https://doi.org/10.1017/S1431927619005646 Published: 01 August 2019