Synopsis: Multiple entanglements

Researchers report entanglement of many cavity modes using an optical frequency comb.
Synopsis figure
Credit: M. Pysher et al., Phys. Rev. Lett. (2011)

Quantum computers might one day allow exponential speedups in tasks such as large-integer factoring, but there is a price: the need to precisely control and coordinate many fragile qubits in a series of error-free steps. Among the proposals for achieving this, one “top-down” architecture relies on the normal modes of an optical system (think of a set of quantum harmonic oscillators) to act as qubits. The trick is to create and manipulate entanglement of these modes, called Qmodes, in ways suitable for information processing. In a paper in Physical Review Letters, Matthew Pysher at the University of Virginia, US, and colleagues now report the largest collection of Qmodes to date and suggest how the technique might be scaled to encompass more.

To generate the Qmodes, the authors use an optical parametric oscillator, a device with the handy ability to take a single photon as input and emit two entangled photons. The parametric oscillator can be driven to create an optical frequency comb, which is a series of Qmodes separated by known frequencies and precisely related to each other in phase. Pysher et al. were able to engineer 15 groups of four entangled Qmodes each, for a total of 60. However, this was only the number of entangled modes they could measure; the authors believe that substantially more modes, perhaps as many as 150 groups, were actually created. With this result, the authors hope to set a course for massive entanglement of many modes into a single group, a prerequisite for any all-optical quantum computer. – David Voss

Note added (19 July 2011): The text has been revised to reflect the fact that Pysher et al. study continuous-value modes (Qmodes) and not qubits (quantum binary digits).


More Features »


More Announcements »

Subject Areas

Quantum Information

Next Synopsis

Strongly Correlated Materials

Majorana states thrive under interactions

Read More »

Related Articles

Synopsis: Entangled Photon Source Ticks All Boxes
Quantum Physics

Synopsis: Entangled Photon Source Ticks All Boxes

A quantum-dot-based device combines all of the attributes necessary for producing a reliable source of entangled photons for quantum information applications.  Read More »

Viewpoint: Alkaline Atoms Held with Optical Tweezers
Quantum Information

Viewpoint: Alkaline Atoms Held with Optical Tweezers

Three separate groups demonstrate the trapping of two-electron atoms in arrays of optical tweezers, opening up new opportunities for quantum simulation and many-body studies. Read More »

Synopsis: A Possible Quantum Computing Boost 
Quantum Information

Synopsis: A Possible Quantum Computing Boost 

A hybrid quantum-classical computing algorithm could solve a basic computer science problem faster than a classical computer. Read More »

More Articles