Synopsis: Opening the gate to quantum computation

The demonstration of entanglement between two neutral atoms would be a key step toward using them for quantum computation.
Synopsis figure
L. Isenhower et al., Phys. Rev. Lett (2010)

Entanglement lies at the heart of quantum computation. Entangling neutral atoms is attractive because they interact weakly with their environment, but by the same token, they are difficult to entangle compared with strongly interacting ions. Papers appearing simultaneously in Physical Review Letters demonstrate how separate groups are achieving entanglement between two neutral atoms by using a method called Rydberg blockade.

The underlying idea behind Rydberg blockade is that the state of one atom (the control) determines whether the other (the target) can be excited into a high-energy state. This effective coupling between the two atoms turns them into a collectively two-level system.

Tatjana Wilk and colleagues at the Institut d’Optique (CNRS and Université Paris-Sud) in France use the Rydberg blockade to entangle 87Rb atoms that are held a few microns apart by optical tweezers. In a separate paper, Larry Isenhower and colleagues at the University of Wisconsin, US, report similar methods to create a two-qubit controlled-NOT (CNOT) gate between 87Rb atoms. The CNOT gate then serves as a means to achieve entanglement between the atoms.

Both groups report the preparation of quantum states with an accuracy (or, fidelity) that is near the threshold needed to prove entanglement; correcting for losses associated with atoms that fell out of the optical traps suggests that the remaining pairs of atoms are entangled with a fidelity well over the threshold. Although there is still work to be done in fine tuning the methods reported by both groups, the papers collectively show important progress toward quantum processing with neutral atoms. – Jessica Thomas and Sonja Grondalski


Announcements

More Announcements »

Subject Areas

Atomic and Molecular PhysicsQuantum Information

Previous Synopsis

Mesoscopics

The space between

Read More »

Next Synopsis

Atomic and Molecular Physics

Simulating a molecule

Read More »

Related Articles

Focus: Strong Light Reflection from Few Atoms
Optics

Focus: Strong Light Reflection from Few Atoms

Up to 75% of light reflects from just 2000 atoms aligned along an optical fiber, an arrangement that could be useful in photonic circuits. Read More »

Synopsis: Controlling a Laser’s Phase
Optics

Synopsis: Controlling a Laser’s Phase

A compact scheme can directly modulate the phase of a laser without a bulky external modulator. Read More »

Focus: Chip Changes Photon Color While Preserving Quantumness
Photonics

Focus: Chip Changes Photon Color While Preserving Quantumness

A new device that can potentially be scaled up for quantum computing converts visible light to infrared light suitable for fiber-optic transmission without destroying the light’s quantum state. Read More »

More Articles