Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantum phase transition observed for the first time

02.02.2017

Photon-blockade breakdown observed experimentally -- Theoretical predictions verified

A group of scientists led by Johannes Fink from the Institute of Science and Technology Austria (IST Austria) reported the first experimental observation of a first-order phase transition in a dissipative quantum system.


This is the probability distribution showing the equal likelihood for the cavity being transparent and opaque at the critical point.

Credit: J. Fink

Phase transitions are something we often encounter in everyday life when we watch the change of the state of matter, for example the freezing of water at the critical temperature of 0 degrees Celsius. However, phase transitions also occur at the quantum mechanical level, where they are - in spite of their importance for various fields of physics - relatively unexplored.

One example of a phase transition at the quantum level is the photon-blockade breakdown, which was only discovered two years ago. During photon blockade, a photon fills a cavity in an optical system and prevents other photons from entering the same cavity until it leaves, hence blocking the flow of photons.

But if the photon flux increases to a critical level, a quantum phase transition has been predicted to occur: The photon blockade breaks down, and the state of the system changes from opaque to transparent. This specific phase transition has now been experimentally observed by researchers who, for the first time, managed to meet the very specific conditions that are necessary to fully study this effect.

During a phase transition, the continuous tuning of an external parameter, for example temperature, leads to a transition between two robust steady states with different attributes. First-order phase transitions are characterized by a coexistence of the two stable phases when the control parameter is within a certain range close to the critical value.

The two phases form a mixed-phase in which some parts have completed the transition and others have not, like in a glass in which ice and water are present at the same time. The experimental results that Fink and his collaborators will publish in the journal Physical Review X give an insight into the quantum mechanical basis of this effect in a microscopic, zero-dimensional system.

Their setup consisted of a microchip with a superconducting microwave resonator acting as the cavity and a few superconducting qubits acting as the atoms. The chip was cooled to a temperature astoundingly close to absolute zero - 0.01 Kelvin - so that thermal fluctuations did not play a role. To produce a flux of photons, the researchers then sent a continuous microwave tone to the input of the resonator on the chip.

On the output side they amplified and measured the transmitted microwave flux. For certain input powers they detected a signal flipping stochastically between zero transmission and full transmission: the expected coexistence of both phases had occurred. "We have observed this random switching between opaque and transparent for the first time and in agreement with theoretical predictions," says lead author Johannes Fink from IST Austria.

Potential future applications are memory storage elements as well as processors for quantum simulation. "Our experiment took exactly 1.6 milliseconds to complete for any given input power. The corresponding numerical simulation took a couple of days on a national supercomputer cluster. This gives an idea why these systems could be useful for quantum simulations," Fink explains.

Johannes Fink came to IST Austria in 2016 to start his working group on Quantum Integrated Devices. The main objective of his group is to advance and integrate quantum technology for chip-based computation, communication, and sensing.

Media Contact

Elisabeth Guggenberger
elisabeth.guggenberger@ist.ac.at
43-022-439-000-1199

 @istaustria

http://www.ist.ac.at 

Elisabeth Guggenberger | EurekAlert!

More articles from Physics and Astronomy:

nachricht Astronomers release most complete ultraviolet-light survey of nearby galaxies
18.05.2018 | NASA/Goddard Space Flight Center

nachricht A quantum entanglement between two physically separated ultra-cold atomic clouds
17.05.2018 | University of the Basque Country

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>