TY - JOUR

T1 - Laser cooling a membrane-in-the-middle system close to the quantum ground state from room temperature

AU - Saarinen, Sampo A.

AU - Kralj, Nenad

AU - Langman, Eric C.

AU - Tsaturyan, Yeghishe

AU - Schliesser, Albert

PY - 2023/3/20

Y1 - 2023/3/20

N2 - Many protocols in quantum science and technology require initializing a system in a pure quantum state. In the context of the motional state of massive resonators, this enables studying fundamental physics at the elusive quantum-classical transition, and measuring force and acceleration with enhanced sensitivity. Laser cooling has been a method of choice to prepare mechanical resonators in the quantum ground state, one of the simplest pure states. However, to overcome the heating and decoherence by the thermal bath, this usually has to be combined with cryogenic cooling. Here, we laser-cool an ultracoherent, soft-clamped mechanical resonator close to the quantum ground state directly from room temperature. To this end, we implement the versatile membrane-in-the-middle setup with one fiber mirror and one phononic crystal mirror, which reaches a quantum cooperativity close to unity already at room temperature. We further-more introduce a powerful combination of coherent and measurement-based quantum control techniques, which allows us to mitigate thermal intermodulation noise. The lowest occupancy we reach is 30 phonons, limited by measurement imprecision. Doing away with the necessity for cryogenic cooling should further facilitate the spread of optomechanical quantum technologies. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

AB - Many protocols in quantum science and technology require initializing a system in a pure quantum state. In the context of the motional state of massive resonators, this enables studying fundamental physics at the elusive quantum-classical transition, and measuring force and acceleration with enhanced sensitivity. Laser cooling has been a method of choice to prepare mechanical resonators in the quantum ground state, one of the simplest pure states. However, to overcome the heating and decoherence by the thermal bath, this usually has to be combined with cryogenic cooling. Here, we laser-cool an ultracoherent, soft-clamped mechanical resonator close to the quantum ground state directly from room temperature. To this end, we implement the versatile membrane-in-the-middle setup with one fiber mirror and one phononic crystal mirror, which reaches a quantum cooperativity close to unity already at room temperature. We further-more introduce a powerful combination of coherent and measurement-based quantum control techniques, which allows us to mitigate thermal intermodulation noise. The lowest occupancy we reach is 30 phonons, limited by measurement imprecision. Doing away with the necessity for cryogenic cooling should further facilitate the spread of optomechanical quantum technologies. (c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

KW - OPTOMECHANICAL SYSTEM

KW - CAVITY

KW - RESONATORS

KW - OSCILLATOR

KW - MOTION

U2 - 10.1364/OPTICA.468590

DO - 10.1364/OPTICA.468590

M3 - Journal article

VL - 10

SP - 364

EP - 372

JO - Optica

JF - Optica

SN - 2334-2536

IS - 3

ER -