Condensed Matter Devices: SQUIDS and Semiconductors
The creation of macroscopic systems that can function as if they were individual quantum objects is an active area of JQI research. This is possible because some quantum effects occur on relatively large spatial scales. One of them is the phenomenon known as "tunneling," in which electrons can pass across an insulating barrier in superconducting structures called Josephson junctions. Although they are small by ordinary standards (on the order of a micron, or millionth of a meter), the junctions are about 10,000 times larger than an individual atom.
One or more of these devices can be arranged so that each one takes on the hallmark property of an atomic qubit: superposition of states. Moreover, the states of different Josephson junctions, or "artificial atoms," can be entangled to provide the same sort of information-transfer and logic-gate potential found in atomic qubits. JQI researchers are testing various configurations of these junctions to find optimal designs and improve performance.
Additionally, the Physics Frontier Center at JQI supports an experiment that seeks to couple ultracold atoms with superconducting qubits. Such a hybrid quantum system combines some of the advantages of two platforms, thus offering another path in developing scalable quantum information architectures.
Semiconducting materials are another scheme for realizing quantum devices. Two-dimensional electron gases can be formed at the interface of two semiconductors. This system offers a playground for studying quantum physics in reduced dimensions. JQI researchers also study how semiconductor devices on atomic-size scale can be utilized for quantum computing.
JQI Experimental Research Groups
JQI Theoretical Research Groups