Yale scientists bring quantum optics to a microchip

Sep 08, 2004

A report in the journal Nature describes the first experiment in which a single photon is coherently coupled to a single superconducting qubit (quantum bit or "artificial atom"). This represents a new paradigm in which quantum optics experiments can be performed in a micro-chip electrical circuit using microwaves instead of visible photons and lasers. The work is a collaboration of the laboratory of Professor Robert Schoelkopf and the theory group of Professor Steven Girvin in the Departments of Applied Physics and Physics at Yale University.

The Yale researchers have constructed a miniaturized superconducting cavity whose volume is more than one million times smaller than the cavities used in corresponding current atomic physics experiments. The microwave photon is, therefore, "trapped" allowing it to be repeatedly absorbed and reemitted by the 'atom' many times before it escapes the cavity. The 'atom' is a superconducting circuit element containing approximately one billion aluminum atoms acting in concert.

Because of the tiny cavity volume and large 'atom' size, the photon and 'atom' are very strongly coupled together and energy can be rapidly exchanged between them. Under the peculiar rules of quantum mechanics, the state of the system becomes a coherent superposition of two simultaneous possibilities: the energy is either an excitation of the atom, or it is a photon. It is this superposition that was observed in the Yale experiment.

In addition to allowing fundamental tests of quantum mechanics and quantum optics in a completely new format, this new system has many desirable features for a quantum computer. In a quantum computer the bits of information are replaced by qubits (e.g. an atom), which, paradoxically, can harness quantum uncertainty to vastly speed up certain types of calculations. The ability to couple qubits to photons, demonstrated by the Yale group, could allow qubits on a chip to be wired together via a "quantum information bus" carrying single photons.

Source: Yale University

Explore further: Caging of molecules allows investigation of equilibrium thermodynamics

add to favorites email to friend print save as pdf

Related Stories

Improving energy efficiency one atom at a time

Feb 17, 2015

Paul Simmonds looks at his molecular beam epitaxy (MBE) system the way other guys do a candy apple red Porsche. The sci-fi looking machine used to design and create new materials at the atomic level lights ...

Scientists track quantum errors in real time

Jul 14, 2014

(Phys.org) —Scientists at Yale University have demonstrated the ability to track real quantum errors as they occur, a major step in the development of reliable quantum computers. They report their results ...

Progress in the fight against quantum dissipation

Apr 16, 2014

(Phys.org) —Scientists at Yale have confirmed a 50-year-old, previously untested theoretical prediction in physics and improved the energy storage time of a quantum switch by several orders of magnitude. ...

Recommended for you

Semiconductor miniaturisation with 2D nanolattices

Feb 26, 2015

A European research project has made an important step towards the further miniaturisation of nanoelectronics, using a highly-promising new material called silicene. Its goal: to make devices of the future ...

Ultra-small block 'M' illustrates big ideas in drug delivery

Feb 26, 2015

By making what might be the world's smallest three-dimensional unofficial Block "M," University of Michigan researchers have demonstrated a nanoparticle manufacturing process capable of producing multilayered, precise shapes.

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.