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Focus: Atomic Clock Beats the Quantum Limit

Don Monroe

Researchers beat the quantum-mechanical fluctuations in an atomic clock by linking many atoms into an entangled quantum state and pushing the fluctuations into a realm that doesn’t influence the time measurement.

Jun 25, 20101 citation

Pushing the Limits of Quantum Sensing with Variational Quantum Circuits

Patrick J. Coles

Variational quantum algorithms could help researchers improve the performance of optical atomic clocks and of other quantum-metrology schemes.By

PhysicsDec 6, 20213 citations

Near-Heisenberg-Limited Atomic Clocks in the Presence of Decoherence

Johannes Borregaard, Anders Søndberg Sørensen

The ultimate stability of atomic clocks is limited by the quantum noise of the atoms. To reduce this noise it has been suggested to use entangled atomic ensembles with reduced atomic noise. Potentially this can push the stability all the way to the limit allowed by the Heisenberg uncertainty relation, which is denoted the Heisenberg limit. In practice, however, entangled states are often more prone to decoherence, which may prevent reaching this performance. Here we present an adaptive measurement protocol that in the presence of a realistic source of decoherence enables us to get near-Heisenberg-limited stability of atomic clocks using entangled atoms. The protocol may thus realize the full potential of entanglement for quantum metrology despite the detrimental influence of decoherence.The ultimate stability of atomic clocks is limited by the quantum noise of the atoms. To reduce this noise it has been suggested to use entangled atomic ensembles with reduced atomic noise. Potentially this can push the stability all the way to the limit allowed by the Heisenberg uncertainty relation, which is denoted the Heisenberg limit. In practice, however, entangled states are often more prone to decoherence, which may prevent reaching this performance. Here we present an adaptive measurement protocol that in the presence of a realistic source of decoherence enables us to get near-Heisenberg-limited stability of atomic clocks using entangled atoms. The protocol may thus realize the full potential of entanglement for quantum metrology despite the detrimental influence of decoherence.

arXiv:1304.2288Physical Review LettersAug 27, 201381 citations

Viewpoint: Keeping atoms synchronized for better timekeeping

Kurt Gibble

In a new regime for atomic clocks, strong interactions between atoms dramatically increase the clock’s coherence time.

Jul 6, 20100 citations

An atomic frequency micrometer based on the coherent population beating phenomenon

Zhong Wang, Jianye Zhao, Xiao-Na Zhao +3 more

We have demonstrated an atomic frequency micrometer based on the coherent population beating phenomenon, which enables us to obtain the beat frequency between the measured signal and the atomic transition frequency. The beat frequency and its fluctuations are detected and accurately measured through digital signal processing, which is capable of up to mHz or higher frequency resolutions (for GHz signal). The frequency discrimination via our method is comparable to that of the Ramsey fringes method, and the working range is no longer limited by the width of line shape. This enables us to achieve an atomic clock by actively compensating the frequency shift, which eliminates the need for a phase locking loop, and broadens the working range with increasing reliability. This novel scheme could be extended to the optical frequency region, implying possible future applications in optical atomic clocks, optical frequency comb, atomic spectroscopy and other related researches.We have demonstrated an atomic frequency micrometer based on the coherent population beating phenomenon, which enables us to obtain the beat frequency between the measured signal and the atomic transition frequency. The beat frequency and its fluctuations are detected and accurately measured through digital signal processing, which is capable of up to mHz or higher frequency resolutions (for GHz signal). The frequency discrimination via our method is comparable to that of the Ramsey fringes method, and the working range is no longer limited by the width of line shape. This enables us to achieve an atomic clock by actively compensating the frequency shift, which eliminates the need for a phase locking loop, and broadens the working range with increasing reliability. This novel scheme could be extended to the optical frequency region, implying possible future applications in optical atomic clocks, optical frequency comb, atomic spectroscopy and other related researches.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)Apr 1, 20154 citations

Squeezing More out of Atomic Clocks

Katherine Wright

Quantum effects can nearly double the precision of a state-of-the-art optical atomic clock, a finding that could allow the devices to search for possible fluctuations in fundamental constants of the Universe.

PhysicsJan 16, 20240 citations

Atomic Clock Beats the Quantum Limit

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Atomic Clock Beats the Quantum Limit

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