photons

They are developing a new concept built on quantum spherical codes that could make the notoriously fragile information in a photon-based quantum computer less susceptible to errors.

The researchers are part of a team that won the quantum category at the university’s Invention of the Year Awards for developing a new method to count particles of light—known as photons—without destroying them.

A team of JQI researchers and their colleagues have won in the quantum category of the UMD Invention of the Year Award. They are honored for developing a new method for counting particles of light—photons—without destroying them.

Flashlight beams don’t clash together like lightsabers because individual units of light—photons—generally don’t interact with each other. Two beams don’t even flicker when they cross paths. But by using matter as an intermediary, scientists have unlocked a rich world of photon interactions. In these early days of exploring the resulting possibilities, researchers are tackling topics like producing indistinguishable single photons and investigating how even just three photons form into basic molecules of light. The ability to harness these exotic behaviors of light is expected to lead to advances in areas such as quantum computing and precision measurement. In a paper recently published in Physical Review Research, JQI Fellow Alexey Gorshkov, JQI postdoctoral researcher Przemyslaw Bienias, and their colleagues describe an experiment that investigates how to extract a train of single photons from a laser packed with many photons.  In the experiment, the researchers examined how photons in a laser beam can interact through atomic intermediaries so that most photons are scattered out of the beam and only a single photon is transmitted at a time. They also developed an improved model that makes better predictions for more intense levels of light than previous research focused on. The new results reveal details about the work to be done to conquer the complexities of interacting photons. 

The concept of temperature is critical in describing many physical phenomena, such as the transition from one phase of matter to another. Turn the temperature knob and interesting things can happen. But other knobs might be just as important for studying some phenomena. One such knob is chemical potential, a thermodynamic parameter first introduced in the nineteenth century by scientists for keeping track of potential energy absorbed or emitted by a system during chemical reactions.In these reactions different atomic species rearranged themselves into new configuration while conserving the overall inventory of atoms. That is, atoms could change their partners but the total number of identity of the atoms remained invariant.

From NIST TechBeat--It’s not lightsaber time, not yet. But a team including theoretical physicists from JQI and NIST has taken another step toward building objects out of photons, and the findings, recently published in Physical Review Letters, hint that weightless particles of light can be joined into a sort of “molecule” with its own peculiar force. Researchers show that two photons, depicted in this artist’s conception as waves (left and right), can be locked together at a short distance. Under certain conditions, the photons can form a state resembling a two-atom molecule, represented as the blue dumbbell shape at center. The arrangement is akin to the way that two hydrogen atoms sit next to each other in a hydrogen molecule.

Topology -- the understanding of how things are connected -- remains abstract, even with the popular example of doughnuts and coffee cups. This concept, esoteric as it appears, is also neat because it is the basis for creating ultrastable quantum "playgrounds."  In topological systems, certain quantum behaviors can be carefully probed and even harnessed for all kinds of practical applications—from metrology to electronics.

Alexey Gorshkov, formerly of CalTech and Harvard, recently joined the JQI as a new Fellow. His research group can be found at http://groups.jqi.umd.edu/gorshkov/. This is a news item released earlier this week by Harvard University. While at CalTech, Gorshkov collaborated with the research groups of M. Lukin and V. Vuletic and contributed theoretical modeling to this research, published this week in Nature.