Related Experiment Video
Updated: Jul 20, 2026
09:23
Quantum State Engineering of Light with Continuous-wave Optical Parametric Oscillators
Published on: May 30, 2014
Generation of spin squeezing via continuous quantum nondemolition measurement
1Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.
Physical Review Letters
|September 6, 2000
Summary
Researchers achieved continuous quantum nondemolition monitoring of atomic spin using lasers. This method produced squeezed atomic spin states, reducing spin noise by 70% below the standard quantum limit.
Area of Science:
- Atomic physics
- Quantum optics
- Quantum measurement
Background:
- Quantum nondemolition (QND) measurement is crucial for precise quantum state monitoring.
- Collective atomic spin states are fundamental in quantum information processing and metrology.
- The standard quantum limit (SQL) represents the minimum noise achievable with classical measurement techniques.
Purpose of the Study:
- To demonstrate continuous quantum nondemolition monitoring of a collective atomic spin.
- To generate squeezed atomic spin states.
- To investigate spin noise reduction below the SQL.
Main Methods:
- Utilized an off-resonant laser beam for probing the collective atomic spin.
- Implemented a continuous measurement scheme to avoid disturbing the quantum state.
- Analyzed the spin noise spectrum to quantify the achieved squeezing.
Main Results:
- Successfully performed continuous quantum nondemolition monitoring of atomic spin.
- Generated squeezed atomic spin states.
- Achieved spin noise reduction of 70% below the standard quantum limit for a coherent spin state.
Conclusions:
- Continuous QND monitoring is a viable technique for preparing and characterizing non-classical atomic states.
- The demonstrated squeezing surpasses the SQL, opening possibilities for enhanced precision measurements.
- This work advances the development of quantum sensors and quantum information processing protocols.
Related Concept Videos
01:03Atomic Nuclei: Nuclear Spin State Overview
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...
01:08NMR Spectroscopy: Spin–Spin Coupling
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved in...
01:08Spin–Spin Coupling Constant: Overview
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
01:12Double Resonance Techniques: Overview
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...