信じられないほど精密な新しい装置で、ダークエネルギーの探索範囲を狭める(With a new, incredibly precise instrument, Berkeley researchers narrow search for dark energy)

2024-06-26 カリフォルニア大学バークレー校(UCB)

＜関連情報＞

• https://news.berkeley.edu/2024/06/26/with-a-new-incredibly-precise-instrument-berkeley-researchers-narrow-search-for-dark-energy/
• https://www.nature.com/articles/s41586-024-07561-3
• https://www.nature.com/articles/s41567-024-02518-9

格子原子干渉計で重力引力を測定する Measuring gravitational attraction with a lattice atom interferometer

Cristian D. Panda,Matthew J. Tao,Miguel Ceja,Justin Khoury,Guglielmo M. Tino & Holger Müller
Nature  Published:26 June 2024
DOI:https://doi.org/10.1038/s41586-024-07561-3

Abstract

Despite being the dominant force of nature on large scales, gravity remains relatively elusive to precision laboratory experiments. Atom interferometers are powerful tools for investigating, for example, Earth’s gravity¹, the gravitational constant², deviations from Newtonian gravity^3,4,5,6 and general relativity⁷. However, using atoms in free fall limits measurement time to a few seconds⁸, and much less when measuring interactions with a small source mass^2,5,6,9. Recently, interferometers with atoms suspended for 70 s in an optical-lattice mode filtered by an optical cavity have been demonstrated^{10,11,12,13,14}. However, the optical lattice must balance Earth’s gravity by applying forces that are a billionfold stronger than the putative signals, so even tiny imperfections may generate complex systematic effects. Thus, lattice interferometers have yet to be used for precision tests of gravity. Here we optimize the gravitational sensitivity of a lattice interferometer and use a system of signal inversions to suppress and quantify systematic effects. We measure the attraction of a miniature source mass to be a_mass = 33.3 ± 5.6_stat ± 2.7_syst nm s⁻², consistent with Newtonian gravity, ruling out ‘screened fifth force’ theories^3,15,16 over their natural parameter space. The overall accuracy of 6.2 nm s⁻² surpasses by more than a factor of four the best similar measurements with atoms in free fall^5,6. Improved atom cooling and tilt-noise suppression may further increase sensitivity for investigating forces at sub-millimetre ranges^17,18, compact gravimetry^19,20,21,22, measuring the gravitational Aharonov–Bohm effect^9,23 and the gravitational constant², and testing whether the gravitational field has quantum properties²⁴.

格子原子干渉計における1分スケールのコヒーレンス限界 Coherence limits in lattice atom interferometry at the one-minute scale

Cristian D. Panda,Matthew Tao,James Egelhoff,Miguel Ceja,Victoria Xu & Holger Müller
Nature Physics  Published:11 June 2024
DOI:https://doi.org/10.1038/s41567-024-02518-9

Abstract

In quantum metrology and quantum simulation, a coherent non-classical state must be manipulated before unwanted interactions with the environment lead to decoherence. In atom interferometry, the non-classical state is a spatial superposition, where each atom coexists in multiple locations as a collection of phase-coherent partial wavepackets. These states enable precise measurements in fundamental physics and inertial sensing. However, atom interferometers usually use atomic fountains, where the available interrogation time is limited to around 3 s for a 10 m fountain. Here we realize an atom interferometer with a spatial superposition state that is maintained for as long as 70 s. We analyse the theoretical and experimental limits to coherence arising from collective dephasing of the atomic ensemble. This reveals that the decoherence rate slows down markedly at hold times that exceed tens of seconds. These gains in coherence may enable gravimetry measurements, searches for fifth forces or fundamental probes into the non-classical nature of gravity.