Tracking the flow of quantum information

November 17, 2016, Yale University
A Yale-led group of researchers has derived a formula for understanding where quantum objects land when they are transmitted. Credit: Illustration by Michael S. Helfenbein/Yale University

If objects in motion are like rainwater flowing through a gutter and landing in a puddle, then quantum objects in motion are like rainwater that might end up in a bunch of puddles, all at once. Figuring out where quantum objects actually go has frustrated scientists for years.

Now a Yale-led group of researchers has derived a formula for understanding where land when they are transmitted. It's a development that offers insight for controlling open quantum systems in a variety of situations.

"The formula we derive turns out to be very useful in operating a quantum computer," said Victor Albert, first author of a study published in the journal Physical Review X. "Our result says that, in principle, we can engineer 'rain gutters' and 'gates' in a system to manipulate quantum objects, either after they land or during their actual flow."

In this case, the gutters and gates represent the idea of dissipation, a process that is usually destructive to fragile quantum properties, but that can sometimes be engineered to control and protect those properties.

The principal investigator of the research is Liang Jiang, assistant professor of applied physics and physics at Yale.

It is a fundamental principle of nature that objects will move until they reach a state of minimal energy, or grounding. But in quantum systems, there can be multiple groundings because can exist in multiple states at the same time—what is known as superposition.

That's where the gutters and gates come in. Jiang, Albert, and their colleagues used these mechanisms to formulate the probability of quantum objects landing in one spot or the other. The formula also showed there was one situation in which superposition can never be sustained: when a quantum "droplet" in superposition has landed in one "puddle" already, but hasn't yet arrived at the other "puddle."

"In other words, such a always loses some of its quantum properties as the 'droplet' flows completely into both puddles," Albert said. "This is in some ways a negative result, but it is a bit surprising that it always holds."

Both aspects of the formula will be helpful in building quantum computers, Albert noted. As the research community continues to develop technological platforms capable of supporting such systems, Albert said, it will need to know "what is and isn't possible."

Explore further: Researchers prevent quantum errors from occurring by continuously watching a quantum system

Related Stories

Finding patterns in 'electron puddles'

August 23, 2016

Yale physicist Leonid Glazman has developed a quantitative theory to explain the effect of quantum and thermal fluctuations of charge in tiny "electron puddles" for a study reported in the journal Nature.

Physicists quantify the usefulness of 'quantum weirdness'

April 13, 2016

(—For the past 100 years, physicists have been studying the weird features of quantum physics, and now they're trying to put these features to good use. One prominent example is that quantum superposition (also ...

Scientists realize quantum bit with a bent nanotube

July 29, 2013

One of the biggest challenges in quantum science is to build a functioning quantum bit, the basic element for the quantum computer. An important theoretical candidate for such a quantum bit is using a bent carbon nanotube. ...

Recommended for you

Muons spin tales of undiscovered particles

April 20, 2018

Scientists at U.S. Department of Energy (DOE) national laboratories are collaborating to test a magnetic property of the muon. Their experiment could point to the existence of physics beyond our current understanding, including ...

Integrating optical components into existing chip designs

April 19, 2018

Two and a half years ago, a team of researchers led by groups at MIT, the University of California at Berkeley, and Boston University announced a milestone: the fabrication of a working microprocessor, built using only existing ...


Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Nov 17, 2016
You do know you are using the wave equation to define "atomic phenomena", quanta; randomness and statistics over the wave equation as some enumerated quanta. You still use mass as your impediment to motion and cannot see that everything is made of diametrical spherical fields, well tabulated; however, without a proper axiomatic structure! You describes these quantized events as particles and there is no fundamental definition and axiomatic structure for a particle. We cannot see the superposition and motion of these ghostly objects that occupy all space, never created or destroyed, updated with respect to its motion at the speed of light!
not rated yet Nov 17, 2016
These objects create everything! The field carries the same directional vector as the center. When you see a wavelet. that wavelet defines the relative motion of the source, given its initial wavelength, and that motion is described by the initial_wave_length/Period. Then the relative velocity is +/- c * lambda_emitted/lambda_observed is the speed. The poynting vector may be resolved. Would one be able to define direction with refraction?
not rated yet Nov 17, 2016
So why not use these?

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.