Science & Technology

Researchers Use Light to Manipulate a Quantum Bit

An artist’s rendering of all-optical management of a person digital spin inside a diamond. This spin is related to a naturally occurring defect in diamond generally known as the nitrogen-vacancy middle, a promising quantum bit (qubit) for quantum info processing. Of their not too long ago printed paper, Yale et al. develop methods to initialize, manipulate, and skim out the digital spin of this qubit utilizing solely pulses of sunshine. Picture courtesy of Peter Allen.

UC Santa Barbara researchers developed an all-optical scheme for controlling particular person quantum bits in semiconductors utilizing pulses of sunshine, opening up new paths towards the creation of quantum computer systems.

Santa Barbara, California –– By utilizing gentle, researchers at UC Santa Barbara have manipulated the quantum state of a single atomic-sized defect in diamond –– the nitrogen-vacancy middle –– in a technique that not solely permits for extra unified management than typical processes, however is extra versatile, and opens up the potential of exploring new solid-state quantum methods. Their results are published in the latest edition of the Proceedings of the National Academy of the Sciences.

“In distinction to typical electronics, we developed an all-optical scheme for controlling particular person quantum bits in semiconductors utilizing pulses of sunshine,” mentioned David Awschalom, director of UCSB’s Middle for Spintronics & Quantum Computation, professor of physics and {of electrical} and pc engineering, and the Peter J. Clarke director of the California NanoSystems Institute. “This discovering provides an intriguing alternative for processing and speaking quantum info with photonic chips.”

The nitrogen-vacancy (NV) middle is a defect within the atomic construction of a diamond the place one carbon atom within the diamond lattice is changed by a nitrogen atom, and an adjoining website within the lattice is vacant. The ensuing digital spin across the defect types a quantum bit –– “qubit” –– which is the fundamental unit of a quantum pc. Present processes require this qubit be initialized into a well-defined vitality state earlier than interfacing with it. In contrast to classical computer systems, the place the fundamental unit of knowledge, the bit, is both 0 or 1, qubits will be 0, 1, or any mathematical superposition of each, permitting for extra advanced operations.

“The preliminary downside we had been making an attempt to clear up was to work out a means that we might place our qubit into any doable superposition of its state in a single step,” mentioned the paper’s first creator, physics graduate scholar Christopher Yale. “It seems that as well as to having the ability to try this simply by adjusting the laser gentle interacting with our spin, we found that we might generate coherent rotations of that spin state and skim out its state relative to some other state of our selecting utilizing solely optical processes.”

The all-optical management permits for higher versatility in manipulating the NV middle over disparate typical strategies that use microwave fields and exploit defect-specific properties. Whereas the NV middle in diamond is a promising qubit that has been studied extensively for the previous decade, diamonds are difficult to engineer and develop. This all-optical methodology, say the researchers, could enable for the exploration of quantum methods in different supplies which might be extra technologically mature. “In contrast to how the NV middle is often studied, these methods in some methods are extra normal and will doubtlessly allow the examine of unexplored quantum methods,” mentioned UCSB physics graduate scholar Bob Buckley.

Moreover, the all-optical technique additionally has the potential to be extra scalable, famous physics graduate scholar David Christle. “If in case you have an array of those qubits so as, and if you happen to’re making use of typical microwave fields, it turns into tough to discuss to one in all them with out speaking to the others. In precept, with our method in an idealized optical system, you’ll have the option focus the sunshine down onto a single qubit and solely discuss to it.”

Whereas sensible quantum computer systems are nonetheless years and years away, the analysis opens up new paths towards their eventual creation. In accordance to the group, these units could be able to performing sure refined calculations and capabilities much more effectively than at present’s computer systems can –– main to advances in fields as various as encryption and quantum simulation.

UCSB electrical and pc engineering graduate scholar F. Joseph Heremans and postdoctoral researcher Lee Bassett additionally contributed to this examine. Further theoretical work and perception was offered by Guido Burkard, professor of physics on the College of Konstanz, Germany.

Publication: Christopher G. Yale, et al., “All-optical management of a solid-state spin utilizing coherent darkish states,” PNAS, 2013; doi: 10.1073/pnas.1305920110

Picture:  Peter Allen

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