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Listening To Electrons On Quantum Dots

Researchers in Australia and the United States have found a new way to detect changes in charges smaller than one electron.

| February 4, 2013 | In the Lab

AsianScientist (Feb. 4, 2013) – Researchers in Australia and the United States have found a new way to detect changes in charges smaller than one electron.

The research, published in the Physical Review Letters, describes a new, more convenient way to detect changes in charge of a single electron on quantum dots.

Ever since Nobel Prize winner Richard Feynman highlighted the potential of quantum computing in the 1980s, scientists have been attempting to build quantum computers capable of solving some of the largest and most complex problems, with much greater efficiency than conventional computers.

“Electrons confined to quantum dots are very nice systems for storing and manipulating quantum information, where data is encoded in the quantum mechanical aspects of the electron. Our goal is to scale-up a large number of quantum dots to ultimately create a machine to process quantum information – a quantum computer,” said Associate Professor David Reilly, from the ARC Center for Engineered Quantum Systems in the School of Physics at the University of Sydney.

Here, the team has found a new way of detecting charge on the quantum dots using the gate electrodes already in the system.

“Previously, sensitive electrometers which measure minute charges were used to read-out the electron state on quantum dots. These work well, but they are somewhat separate devices built onto the ends of the quantum dot system. They are a bit like having microphones nearby that can pick up the sound of electrons,” Reilly explained.

“What we have shown is that the gates or electrodes that are already in place to create the quantum dot in the first place, can also act as read-out detectors. This means you don’t need separate devices and you don’t need to worry about how to place those separate electrometer devices,” he said.

The new method of detection allows for read-out in large dot arrays with no limitation on the size of the array for the read-out method to work.

“In a similar way to how billions of transistors can now be placed on a single silicon computer chip, in the future we would like to engineer semiconductor chips containing huge numbers of interacting quantum two-level systems – called qubits. The work presented in this paper suggests a new method of reading out qubits that enables this goal,” said James Colless, the lead author on the study.

The article can be found at: Colless JI et al. (2013) Dispersive Readout of a Few-Electron Double Quantum Dot with Fast rf Gate Sensors.

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Source: University of Sydney.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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