28 April 2010
NIST unveils ‘dimmer switch’ for quantum computer
Scientists at the US National Institute of Standards and Technology (NIST) have developed what is being called the first 'dimmer switch' for a superconducting circuit linking a quantum bit (qubit) and a quantum bus.
The NIST switch is a new type of control device that can 'tune' interactions between a quantum bit (or qubit) and a quantum bus and could speed the development of a practical quantum computer.
According to NIST, the switch can reliably tune the interaction strength or rate between qubit and the quantum bus from 100MHz to nearly zero. The advance could enable researchers to control the interactions between many circuit elements in an intricate network, something that would be required in a quantum computer of a practical size.
NIST says its switch is the first to produce predictable quantum behaviour over time with the controllable exchange of an individual microwave photon between a qubit and a resonant cavity, which acts as a bus.
"We have three different elements working together coherently and without losing a lot of energy," said Michael Allman, a graduate of CU-Boulder. Allman performed the experiments with NIST physicist Ray Simmonds, the principal investigator.
All three components (qubit, switch and cavity) were made of aluminium in an overlapping pattern on a sapphire chip. The switch is an rf SQUID (superconducting quantum interference device). The circuit is created with a voltage pulse that places one unit of energy – a single microwave photon—in the qubit. By tuning a magnetic field applied to the SQUID, scientists can alter the coupling energy or transfer rate of the single photon between the qubit and cavity.
Author
Graham Pitcher
Supporting Information
Websites
http://www.nist.gov.uk
Companies
NIST
This material is protected by Findlay Media copyright
See Terms
and Conditions.
One-off usage is permitted but bulk copying is not.
For multiple copies contact the
sales team.