Related Experiment Video
Updated: Dec 12, 2025
10:00
Gradient Echo Quantum Memory in Warm Atomic Vapor
Published on: November 11, 2013
13.1K
Free Space Ramsey Spectroscopy in Rubidium with Noise below the Quantum Projection Limit
Benjamin K Malia1, Julián Martínez-Rincón1, Yunfan Wu2
1Department of Physics, Stanford University, Stanford, California 94305, USA.
Physical Review Letters
|August 16, 2020
Summary
Spin-squeezed atomic states generated in optical cavities improve atomic fountain clock precision. This quantum enhancement significantly surpasses the standard quantum limit for frequency stability in atomic clocks.
Area of Science:
- Atomic Physics
- Quantum Optics
- Metrology
Background:
- Atomic fountain clocks are crucial for precise timekeeping.
- Quantum projection limit traditionally restricts clock sensitivity.
- Spin-squeezed states offer a pathway to overcome these limitations.
Purpose of the Study:
- To demonstrate the utility of optical cavity generated spin-squeezed states in free space atomic fountain clocks.
- To quantify the phase sensitivity and frequency stability achieved using these states.
- To assess the preservation of quantum squeezing during atomic free fall.
Main Methods:
- Utilized ensembles of 87Rb atoms (390,000 atoms).
- Employed fluorescence imaging correlated with quantum nondemolition measurement for population spectroscopy.
- Performed Ramsey spectroscopy with 240,000 atoms after release from a lattice trap.
Main Results:
- Achieved a single-shot phase sensitivity of 814(61) microradians, 5.8(0.6) dB below the quantum projection limit.
- Observed preservation of squeezing as the atomic cloud expanded and fell in free space.
- Attained a single-shot fractional frequency stability of 8.4(0.2)×10^-12, 3.8(0.2) dB below the quantum projection limit.
Conclusions:
- Optical cavity generated spin-squeezed states significantly enhance the performance of atomic fountain clocks.
- The demonstrated squeezing provides a substantial improvement over the standard quantum limit.
- Technical noise in fluorescence detection and microwave systems currently limit further improvements.
Related Concept Videos
01:26Raman Spectroscopy Instrumentation: Overview
846
A conventional Raman spectrophotometer includes a laser source, a sample holding system, a wavelength selector, and a detector.
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...
The monochromatic laser source, typically using visible or near-infrared radiation, generates a highly focused beam of light. This light interacts with the molecules of the sample, scattering some of the light. Liquid and gaseous samples are usually tested in ordinary glass capillaries, while solids can be analyzed as powders packed in capillaries or as potassium...
846
01:20Raman Spectroscopy: Overview
1.1K
The underlying principle of Raman spectroscopy is based on the interaction between light and matter, specifically molecules' inelastic scattering of photons. When a monochromatic beam of light, typically from a laser source, interacts with a sample, most scattered light has the same frequency as the incident light. This is known as Rayleigh scattering.
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and...
However, a small fraction of the scattered light exhibits a frequency shift due to the exchange of energy between the incident photons and...
1.1K
01:14NMR Spectrometers: Resolution and Error Correction
969
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...
969
01:30Atomic Emission Spectroscopy: Interference
498
In atomic emission spectroscopy (AES), high-temperature atomizers excite a broad range of elements and molecules that generate complex emissions from sources such as oxides, hydroxides, and flame combustion products in the flame or plasma. Several strategies can be employed to minimize spectral interferences caused by overlapping emission lines or bands. These include increasing instrument resolution, choosing alternative emission lines, optimally placing the detector in low-background regions,...
498
01:22Atomic Emission Spectroscopy: Instrumentation
1.0K
The instrumentation of atomic emission spectrometry (AES) involves various components, including atomization devices that convert samples into gas-phase atoms and ions. There are two main types of atomization devices: continuous and discrete atomizers. Continuous atomizers, like plasmas and flames, introduce samples in a constant stream, while discrete atomizers inject individual samples using syringes or autosamplers. The most common discrete atomizer is the electrothermal atomizer.
1.0K
01:16IR Spectroscopy: Hooke's Law Approximation of Molecular Vibration
2.5K
A covalently bonded heteronuclear diatomic molecule can be modeled as two vibrating masses connected by a spring. The vibrational frequency of the bond can be expressed using an equation derived from Hooke's law, which describes how the force applied to stretch or compress a spring is proportional to the displacement of the spring. In this case, the atoms behave like masses, and the bond acts like a spring.
According to Hooke's law, the vibrational frequency is directly proportional to...
According to Hooke's law, the vibrational frequency is directly proportional to...
2.5K