Scientists have shown that they can extend the life of a molecular qubit by changing the structure of the surrounding crystal to be less symmetrical. The asymmetry shields the qubit from noise, allowing it to retain information five times longer than if it were housed in a symmetrical structure. Credit: MIT/Dan Laorenza
Stability in asymmetry
By breaking the symmetry of their surroundings, scientists are demonstrating a new technique to extend the length of time qubits can retain information.
What happened
Scientists have shown that by changing the structure of the surrounding crystal to be less symmetrical, they can extend the life of a molecular qubit.
The qubit is shielded from noise by the asymmetry, allowing it to retain information five times longer than if it were housed in a symmetrical structure. The study team achieved a coherence time (the time the qubit retains information) of 10 microseconds, or 10 millionths of a second, compared to a molecular qubit’s coherence time of 2 microseconds in a symmetrical host crystal.
The results, which were published in the journal Physical examination X, were produced by a group of scientists from the Massachusetts Institute of Technology, the US Department of Energy (DOE) Argonne National Laboratory, Northwestern University, the University of Chicago and the University of Glasgow . Q-NEXT, a DOE National Quantum Information Science Research Center run by Argonne, helped fund the research.
A bit of context
- A qubit is the fundamental unit of quantum information, the quantum analogue of a traditional computer bit.
- Qubits can only retain information for a certain amount of time before noise or spurious signals destroy the information. Extending the length of time that information remains stable, known as coherence time, is one of the greatest challenges in quantum information science.
- Qubits are of different types, one of which is a molecule engineered in the laboratory. Molecular qubits are modular, meaning they can be moved from one environment and placed in another easily. In contrast, other types of qubits, such as those made of semiconductors, are strongly tied to their environment.
why is it important
- Longer consistency time: Longer coherence times make qubits more useful in applications such as computing, long-distance communication, and sensing in fields such as medicine, navigation, and astronomy.
- Modularity: Since the coherence time can be lengthened by modifying the qubit’s casing or by placing it in a more asymmetrical position with respect to its casing, it is not necessary to modify the qubit itself to obtain durations of longer lives. Just change his situation.
“Molecular chemistry allows us to swap the crystalline material that hosts the qubit as well as modify the qubit itself,” said Danna Freedman, FG Keyes Professor of Chemistry at
” data-gt-translate-attributes=”[{” attribute=””>MIT and paper co-author. “Adding in this new level of control is very powerful.”
“The change was realized just by interchanging single atoms on the host molecules, one of the smallest changes you could get, and it gave rise to the five-fold enhancement in coherence time,” said the
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