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Photons—the quantum particles of light—normally don’t have any sense of personal space. A laser crams tons of photons into a tight beam, and they couldn’t care less that they are packed on top of each other. Two beams can even pass through each other without noticing. This is all well and good when making an extravagant laser light show or using a laser level to hang a picture frame straight, but for researchers looking to develop quantum technologies that require precise control over just one or two photons, this lack of interaction often makes life difficult. Now, a group of UMD researchers has come together to create tailored interactions between photons in an experiment where, at least for photons, two’s company but three’s a crowd. The technique builds on many previous experiments that use atoms as intermediaries to form connections between photons that are akin to the bonds between protons, electrons and other kinds of matter. These interactions, along with the ability to control them, promises new opportunities for researchers to study the physics of exotic interactions and develop light-based quantum technologies.

When you brush your hair in the morning, there’s a pretty good chance you’re not thinking about quantum physics. But the way your hair swirls as you brush is actually related to some features of the quantum world. Important properties of quantum particles are described by topology—a field of mathematics that classifies objects according to how many holes they have. This is not merely a question of fashion. In physical materials, topology can determine many interesting properties. Now, a team of JQI researchers has engineered a new kind of topological matter—one with a single whorl—by breaking free from the constraints of crystalline solids. They managed to do this by grooming their atomic states into a whorl situated in an abstract, infinite plane, rather than a coconut or donut shape.

JQI Fellow Jake Taylor has been recognized by the federal government for his role in expanding U.S. policy and efforts in the fiercely competitive field of quantum information science. Taylor, who is also a physicist at the National Institute of Standards and Technology (NIST), is the recipient of the 2020 Gold Medal Award from the Department of Commerce.

One of the chief obstacles facing quantum computer designers—correcting the errors that creep into a processor’s calculations—could be overcome with a new approach by physicists from and the California Institute of Technology, who may have found a way to design quantum memory switches that would self-correct. The team’s theory paper, which was published Dec. 8, 2020 in the journal Physical Review Letters, suggests an easier path to creating stable quantum bits, or qubits, which ordinarily are subject to environmental disturbances and errors. Finding methods of correcting these errors is a major issue in quantum computer development, but the research team’s approach to qubit design could sidestep the problem.