Synopsis: Putting the squeeze on many atoms

Squeezed states can enhance the sensitivity of a detector and the storage capability of quantum memory devices. Because these features improve with an increase in system size, researchers are exploring ways to produce squeezed states in large ensembles of atoms.
Synopsis figure

In quantum mechanics, a squeezed state is characterized by two noncommuting observables, where one observable has a small variance at the expense of a large variance in the other, so that the uncertainty principle is satisfied. There is currently interest in preparing macroscopic squeezed states as this would improve the storage capability of quantum memory devices, such as atomic ensembles that store a state of light that can later be read out optically.

A macroscopic spin state—composed of many individual spins—can be squeezed provided that entanglement can be created within the system. Writing in Physical Review Letters, researchers at the Niels Bohr Institute in Copenhagen report the creation of a spin squeezed state in an ensemble of spin-polarized cesium atoms. They take advantage of entanglement between the nuclear and electronic spin states of the individual ground state atoms, rather than between the electronic spin states of different atoms in the ensemble.

At room temperature, about 1012 cesium atoms, each with a total spin of 4, are confined to a glass cell placed in a magnetic field. An applied laser pulse puts about 98% of the atoms into a state maximally polarized along one axis, creating a coherent spin state (a minimum uncertainty state) with macroscopic spin. Another light pulse creates the entanglement necessary to put the ensemble in a squeezed state. A tomographic reconstruction of the final quantum state verified that a collective spin squeezed state was produced. – Sonja Grondalski


Announcements

More Announcements »

Subject Areas

Quantum InformationOptics

Previous Synopsis

Next Synopsis

Related Articles

Synopsis: Starting Fluid for Laser Fusion
Energy Research

Synopsis: Starting Fluid for Laser Fusion

A laser-based fusion experiment demonstrates that liquid fuel capsules could rectify problems encountered with ice-based fuel capsules. Read More »

Synopsis: Graphene’s Elegant Optics Explained
Graphene

Synopsis: Graphene’s Elegant Optics Explained

Theoretical calculations anchor graphene’s simple optical absorption in its two-dimensional structure instead of its cone-shaped energy bands. Read More »

Synopsis: Sharper Vision for Infrared Telescopes
Optics

Synopsis: Sharper Vision for Infrared Telescopes

Converting infrared light to visible light might boost the sensitivity of infrared telescope arrays. Read More »

More Articles