One step closer to quantum computers

Jul 06, 2012
One step closer to quantum computers
Credit: Thinkstock

EU researchers have developed novel ways of producing qubits that enhance their efficiency, potentially bringing the world one step closer to the ‘Holy Grail’ of supercomputing.

Computers based on quantum bits () instead of on standard bits have the potential to perform calculations at an exponentially higher rate than that of standard computers. Quantum computers open up limitless applications to complex numerical calculations – think of the huge difference in capability between a calculator and a computer in terms of quickly executed repetitive calculations.

The power of qubits lies in their ability to exist in more than one state at a given time – no more ‘0’ or ‘1’, now ‘0 and 1’ is also a possibility. However, an interference phenomenon called decoherence has proved a major stumbling block to the performance required for quantum calculation. Decoherence refers to random changes in quantum states, an instability that leads to loss of information.

Thus, the main issue in dealing with qubits is decoherence. A number of designs for qubits are based on the so-called Josephson effect in low critical temperature (Tc) superconductors (LTSs), where the critical temperature is that at which a material becomes superconducting.

The Josephson effect, the ability of electrons to ‘tunnel’ through very thin non-conducting regions in the absence of an applied external voltage, likely arises from incoherence of the electrons in the two superconductors separated by that region. The system of two semiconductors and the typically non-conducting space between them is the Josephson junction (JJ).

European researchers supported by funding of the HYBMQC project seek to demonstrate the feasibility of designing high-quality qubits partly based on the Josephson effect in high Tc superconductors (HTSs) for intrinsic quantum protection against decoherence.

Scientists have conducted numerous experiments comparing LTS and HTS JJs. They focused on alternatives to the conventional niobium (Nb) junctions, including niobium nitride (NbN).

These junctions were characterized by moderately damped regimes (MDRs), with damping able to sustain macroscopic quantum tunnelling at lower temperatures compared to conventional JJs.

HTS JJs appeared to offer comparable functionalities to LTS JJs with more flexibility. Progress in control of HTS JJs led to design of an HTS quantum interference device (rf-SQUID) and the impetus for a new hybrid design and fabrication integrating indium arsenide (InAs) nanowires.

The of the qubits produced by the HYBMQC project team using classical junction platforms opens the way for extension to novel materials with potentially novel functions.

Explore further: Researchers develop the first-ever quantum device that detects and corrects its own errors

add to favorites email to friend print save as pdf

Related Stories

Advancing quantum computing

May 30, 2012

European researchers have made important advances in understanding the major stumbling block to realisation of quantum computers, a phenomenon known as decoherence.

At Yale, quantum computing is a (qu)bit closer to reality

Feb 15, 2012

(PhysOrg.com) -- Physicists at Yale University have taken another significant step in the development of quantum computing, a new frontier in computing that promises exponentially faster information processing ...

Recommended for you

The dark side of cosmology

3 hours ago

It's a beautiful theory: the standard model of cosmology describes the universe using just six parameters. But it is also strange. The model predicts that dark matter and dark energy – two mysterious entities ...

Studying effects of target 'tents' on NIF

3 hours ago

A systematic study of the effects on National Ignition Facility (NIF) implosions of the ultra-thin mounting membranes that support target capsules inside NIF hohlraums was reported by LLNL researchers in ...

Mathematicians model fluids at the mesoscale

3 hours ago

When it comes to boiling water—or the phenomenon of applying heat to a liquid until it transitions to a gas—is there anything left for today's scientists to study? The surprising answer is, yes, quite ...

Breakthrough in nonlinear optics research

Mar 05, 2015

A method to selectively enhance or inhibit optical nonlinearities in a chip-scale device has been developed by scientists, led by the University of Sydney. The researchers from the Centre for Ultrahigh bandwidth ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.