• UCSBgauchos twitter avatar
    Gauchos lead LBSU 60-57 with 47.4 to go
    1 hour 8 min ago
  • UCSBgauchos twitter avatar
    UCSB locked in a tight one but leads LBSU 40-36 with 6:42 to go in the 3rd. Porter has a team-high 13 pts and career-high 8 boards
    1 hour 48 min ago
  • UCSBgauchos twitter avatar
    Gauchos lead 1st place LBSU 22-18 with 7:39 left in the second. Sarah Porter leads all scorers with 10 points on 4-4 shooting
    2 hours 24 min ago
  • UCSBgauchos twitter avatar
    There she goes again! Sarah Porter starts the game 3-3 from the field (2-2 on 3s) and has a game-high 8 points. UCSB trails LBSU 13-14
    2 hours 35 min ago
  • UCSBgauchos twitter avatar
    We're 10 minutes away from tipoff at the T-Dome! UCSB (7-9, 2-1) takes on 1st place Long Beach St (12-6, 3-0) looking for a 3rd straight win
    2 hours 57 min ago
  • UCSB_GradPost twitter avatar
    Forging a career in STEM education: The postdoc stage https://t.co/rutLAfXY7O #UCSB #ucsbgradpost
    5 hours 44 min ago
  • ArtsandLectures twitter avatar
    Dance legend Bill T. Jones retired, but he will perform in Story/Time tomorrow night at the @GranadaSB: https://t.co/WjPeUnYgPY
    6 hours 14 min ago
  • ArtsandLectures twitter avatar
    If the interview with @ProfDBrinkley in @SBIndpndnt left you wanting more, the online version is here to help: https://t.co/7xrjH5TFP3
    6 hours 25 min ago
  • UCSB_GradPost twitter avatar
    Optimize your resume with free Jobscan trial https://t.co/uYaESujgQ7 #UCSB #ucsbgradpost
    7 hours 16 min ago
  • UCSB_GradPost twitter avatar
    Author and activist Tim Wise to speak at Campbell Hall on January 25 https://t.co/ceHDtF0Tpu #UCSB #ucsbgradpost
    9 hours 2 min ago
  • UCSB_GradPost twitter avatar
    Black Graduate Student Association to meet January 23 and February 27 https://t.co/uqAuaPCO1t #UCSB #ucsbgradpost
    9 hours 2 min ago

Quantum Control Protocols Could Lead to More Accurate, Larger Scale Quantum Computations

Wednesday, April 4, 2012 - 17:00
Santa Barbara, CA

2686-1.jpg

David Awschalom

David Awschalom

A protocol for controlling quantum information pioneered by researchers at UC Santa Barbara, the Kavli Institute of Nanoscience in Delft, the Netherlands, and the Ames Laboratory at Iowa State University could open the door to larger-scale, more accurate quantum computations. Their findings, in a paper titled "Decoherence-protected quantum gates for a hybrid solid-state spin register," are published in the current issue of the journal Nature.

"Although interactions between a quantum bit (‘qubit') and its environment tend to corrupt the information it stores, it is possible to dynamically control qubits in a way that facilitates the execution of quantum information-processing algorithms while simultaneously protecting the qubits from environment-induced errors," said UCSB physicist David Awschalom. He and his group were responsible for developing the electron and nuclear spins used as the quantum bits –– the quantum version of the computer bit –– in their demonstration and for helping to analyze the results.

Awschalom is director of UCSB's Center for Spintronics & Quantum Computation, professor of physics, electrical and computer engineering, and the Peter J. Clarke Director of the California NanoSystems Institute.

Dynamical protection of quantum information is essential for quantum computing as the qubits used for information processing and storage are highly susceptible to errors induced by interactions with atoms in the qubits' environment. The scientists' previous research has shown that quantum information stored in qubits can be effectively protected through successive control operations (rotations) on a qubit that filter out these unwanted interactions. However, these control operations also filter out the interactions between qubits that are essential for the realization of logic gates for quantum information processing. Thus, until recently, quantum information stored in protected qubit states could not be used for quantum computations.

The research team, which also included members from the University of Southern California, showed that by precisely synchronizing the rotations of an electron spin with the rotation of a nearby nuclear spin, they could realize dynamical protection of both qubits from the environment while maintaining the interactions between the two spins that are necessary for quantum information processing. As a proof of principle, the researchers demonstrated the high-fidelity execution of a quantum search algorithm using this two-qubit system. Quantum search algorithms, if executed on a larger number of qubits, could provide search results of certain databases considerably faster than search algorithms performed on a classical computer.

The results of this study point to greater possibilities for quantum computers that overcome, according to Awschalom, the perception that spin qubits in semiconductors, such as those used in this work, suffer from too strong of environmental interactions to be useful qubits. These solid state spin systems also offer the added benefit of operating at room temperature, in contrast to other candidate qubit systems which operate at only at a fraction of a degree above absolute zero.

"This demonstration of performing a quantum algorithm at the subatomic level with single spins suggests a pathway to build increasingly complex quantum machines, using qubit control protocols that circumvent the expected limitations from real materials," said Awschalom.

 

 

 

 

 

 


 

 

 

 

 

 

 

[RETURN TO TOP]  

 

 

Middle photo: The quantum circuit used in the demonstration is a 3mm x 3mm chip with a 1mm x 1mm diamond in the middle. Credit: Delft University of Technology/UC Santa

Barbara.

 

†† Bottom photo: A 20 micron x 20 micron magnification of the diamond chip, showing an integrated diamond lens above the single particle spins where the calculations take place.

 

 

The Awschalom Group
The Ames Laboratory
The Kavli Institute for Nanoscience