Synopsis: One Photon Good, Two Better

Quantum interference of pairs of photons emitted by nitrogen-vacancy centers in diamond paves the way for entanglement of distant qubits.
Synopsis figure
H. Bernien et al., Phys. Rev. Lett. (2012)

Although several powerful quantum algorithms have been put forth for quantum computing, implementing them in a physical device requires suitable qubits, protection from decoherence, and ways to read inputs and write outputs. Nitrogen-vacancy centers (NV) in diamond, which are nitrogen atoms coupled to a lattice vacancy, have pushed to the front of the queue of candidate qubits owing to their easily controllable spin states and stable optical properties. The trick now is to find a way to entangle and manipulate pairs of distant qubits for quantum computations. Hannes Bernien of Delft University of Technology, Netherlands, and colleagues now report in Physical Review Letters their progress on this front in the form of two-photon quantum interference of spatially separated diamond NV centers.

Such NV centers have been experimentally well characterized and researchers have entangled NV spins with photons, but the new work by Bernien et al. takes the next step. If two indistinguishable photons, each entangled with a distant NV center, can exhibit quantum interference then this can be exploited to obtain entanglement of the NV centers themselves. The authors have demonstrated exactly this kind of two-photon quantum interference by carefully isolating the optical transitions of separate NV centers and tuning them into resonance with applied electric fields. Moreover, the authors carried out simulations of the experiment with no free parameters that agree well with the interference data. Their work now sets the stage for controllable entanglement of pairs of NV centers in a bulk material and the possibility of building quantum networks of qubits for information processing. – David Voss


Features

More Features »

Announcements

More Announcements »

Subject Areas

Quantum InformationOpticsMaterials ScienceQuantum Physics

Previous Synopsis

Quantum Information

Floating Gates

Read More »

Next Synopsis

Cosmology

Tipping the Balance

Read More »

Related Articles

Viewpoint: Porous Materials Exhibit Granular-Like Stress Chains
Materials Science

Viewpoint: Porous Materials Exhibit Granular-Like Stress Chains

Simulations of porous materials exhibit internal stress patterns like those in granular materials, despite the fact that these two systems are practically “negative images” of each other. Read More »

Focus: Bacteria Form Waveguides
Biological Physics

Focus: Bacteria Form Waveguides

A laser beam sent through a suspension of marine bacteria pulls the organisms into the beam, which focuses the light. Read More »

Viewpoint: The Thermodynamic Cost of Measuring Time
Quantum Physics

Viewpoint: The Thermodynamic Cost of Measuring Time

A simple model of an autonomous quantum clock yields a quantitative connection between the clock’s thermodynamic cost and its accuracy and resolution. Read More »

More Articles