Synopsis: A few good photons

Nonclassical light may provide a more efficient readout mechanism than its classical counterpart in the regime of few photons.
Synopsis figure
Credit: Adapted from

States of an electromagnetic field are called classical when they can be expressed as probabilistic sums of coherent states. Such states describe almost all sources of radiation in everyday technology. By contrast, no such appropriate sum of coherent states can be found for a nonclassical or quantum state. Investigating such states is the business of modern quantum optics laboratories.

Writing in Physical Review Letters, Stefano Pirandola of the University of York, UK, proposes an idealized quantum readout mechanism that takes advantage of the quantum nature of nonclassical states. He describes a digital memory device reminiscent of optical storage media like a DVD.

In his model, digital information is stored in cells with two different reflectivities, representing the two values of a bit. Each cell is then irradiated by light subsequently measured by detectors. When the mean number of photons for each cell is fixed at a low number, the author’s calculations indicate that a nonclassical source of light retrieves significantly more information than a classical one.

Better data transfer at the “few photon” level should give us optical disks that spin faster. This work may also lead to the safe readout of photodegradable memory devices, such as dye-based optical disks or photosensitive microfilms, using faint quantum light to retrieve the data safely, where classical light would be destructive. – Sami Mitra


More Announcements »

Subject Areas

Quantum InformationOptics

Previous Synopsis

Biological Physics

Are eccentric cells better scouts?

Read More »

Next Synopsis


Hyperon stars

Read More »

Related Articles

Synopsis: Time Optimization in Quantum Computing  
Quantum Information

Synopsis: Time Optimization in Quantum Computing  

New experiments find the fastest way to manipulate logic gates with two qubits as inputs. Read More »

Synopsis: Scaling-Up with a Quantum Socket
Quantum Information

Synopsis: Scaling-Up with a Quantum Socket

A three-dimensional mesh of wires could connect large arrays of superconducting qubits in a quantum computer. Read More »

Synopsis: Hydrogen  Bonding Comes to the Rescue
Chemical Physics

Synopsis: Hydrogen Bonding Comes to the Rescue

Hydrogen bonding may safeguard biomolecules against the damaging effects of UV light. Read More »

More Articles