New Amplifier Pushes the Boundary of Quantum Physics

May 05, 2010
Michel Devoret, left, and Rob Schoelkopf conduct a quantum circuit experiment in lab at Yale. Devoret and Schoelkopf are authors of paper published in the journal Nature that describes new way to amplify signals in quantum computers.

(PhysOrg.com) -- If powerful new quantum computers are to reach their enormous potential, they will need amplifiers capable of transmitting signals so weak they consist of a single photon. In the May 6 edition of the journal Nature, a team of Yale scientists report creating an amplifier almost as efficient as the laws of quantum physics allow.

Quantum computers, like cell phones, depend upon sophisticated microwave amplifiers to ensure that information is accurately retrieved. However, all amplifiers contain inherent flaws - most notably flaws which produce random noise that can obscure the signal. In , the Heisenberg uncertainty principle dictates that a small amount of noise is inevitable, no matter how good the amplifier.

“If you want take information out of the computer, you will have to amplify very weak signals,” said Michel Devoret, Frederick William Beinecke Professor of Physics and Applied Physics at Yale’s School of Engineering & Applied Science and senior author of the paper. “The aim of our research is to devise an amplifier for signals so tiny they have only one photon in them.”

“Michel and his team have developed a new design for a practical using superconducting electrical circuits at cryogenic temperatures that comes very close to the ideal limit of this minimum amount of added noise,” said Steven M. Girvin, deputy provost for science and technology, the Eugene Higgins Professor of Physics & Applied Physics at Yale’s School of Engineering & Applied Science and a co-author of the work.

The Yale effort to build a quantum computer based on superconducting electrical circuits relies on incredibly weak microwave signals to both control and measure the quantum state of the computer. The typical signal power that must be measured is on the order of one billionth of one billionth of a watt, equivalent to the power of a cell phone call signal received on the moon from someone on earth.

Other Yale authors on the paper are: Nicola Bergeal, Flavius Schackert, Michael Metcalfe, R. Vijay, Vladimir Manucharyan, Luigi Frunzio, Daniel Prober, and Robert Schoelkopf.

Researchers at the University of Maryland and the University California, Berkeley also contributed to the paper.

Explore further: Team finds elusive quantum transformations near absolute zero

More information: Phase-preserving amplification near the quantum limit with a Josephson ring modulator, Nature, 465, 64-68 (06 May 2010) doi:10.1038/nature09035

Related Stories

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 ...

Recommended for you

Physicists design zero-friction quantum engine

12 hours ago

(Phys.org) —In real physical processes, some energy is always lost any time work is produced. The lost energy almost always occurs due to friction, especially in processes that involve mechanical motion. ...

Fluid mechanics suggests alternative to quantum orthodoxy

Sep 12, 2014

The central mystery of quantum mechanics is that small chunks of matter sometimes seem to behave like particles, sometimes like waves. For most of the past century, the prevailing explanation of this conundrum ...

The sound of an atom has been captured

Sep 11, 2014

Researchers at Chalmers University of Technology are first to show the use of sound to communicate with an artificial atom. They can thereby demonstrate phenomena from quantum physics with sound taking on ...

The quantum revolution is a step closer

Sep 11, 2014

A new way to run a quantum algorithm using much simpler methods than previously thought has been discovered by a team of researchers at the University of Bristol. These findings could dramatically bring ...

User comments : 0