The U.S. Department of Energy’s Ames Laboratory led a team that demonstrated a protected quantum gate in a solid-state system. The physicists (c) isolated the system from forces in the environment while maintaining
coherence between the nucleus and electron in the system. This was a major step forward in quantum information processing beyond simply (a) establishing coherence between parts of a quantum system (but without isolation from the environment) or (b) decoupling all parts of the system from the environment (and each other).
Scientists have overcome a major hurdle facing quantum computing: how to protect quantum information from degradation by the environment while simultaneously performing computation in a solid-state quantum system. The research was reported in the April 5 issue of Nature.
A group led by U.S. Department of Energy’s Ames Laboratory physicist Viatsheslav Dobrovitski and including scientists at Delft University of Technology; the University of California, Santa Barbara; and University of Southern California, made this big step forward on the path to using the motions of single electrons and nuclei for quantum information processing. The discovery opens the door to robust quantum computation with solid-state devices and using quantum technologies for magnetic measurements with single-atom precision at nanoscale.
Quantum information processing relies on the combined motion of microscopic elements, such as electrons, nuclei, photons, ions, or tiny oscillating joists. In classical information processing, information is stored and processed in bits, and the data included in each bit is limited to two values (0 or 1), which can be thought of as a light switch being either up or down. But, in a quantum bit, called a qubit, data can be represented by how these qubits orient and move in relationship with each other, introducing the possibility for data expression in many tilts and movements.
This power of quantum information processing also poses a major challenge: even a minor “bump” off course causes qubits to lose data. And qubits tend to interact quite sensitively with their environment, where multiple forces bump them off track.
But, because the key to quantum information processing is in the relationship between qubits, the solution is not as easy as isolating a single qubit from its environment.
“The big step forward here is that we were able to decouple individual qubits from the environment, so they retain their information, while preserving the coupling between the qubits themselves” said Dobrovitski. …