Chaining atoms together yields quantum storage
New technique could make quantum networking possible

Date:
February 17, 2022
Source:
California Institute of Technology
Summary:
Data stored in spin states of ytterbium atoms can be transferred
to surrounding atoms in a crystal matrix.



FULL STORY ========================================================================== Engineers at Caltech have developed an approach for quantum storage
could help pave the way for the development of large-scale optical
quantum networks.


==========================================================================
The new system relies on nuclear spins -- the angular momentum of an
atom's nucleus -- oscillating collectively as a spin wave. This collective oscillation effectively chains up several atoms to store information.

The work, which is described in a paper published on February 16 in
the journal Nature, utilizes a quantum bit (or qubit) made from an
ion of ytterbium (Yb), a rare earth element also used in lasers. The
team, led by Andrei Faraon (BS '04), professor of applied physics and electrical engineering, embedded the ion in a transparent crystal of
yttrium orthovanadate (YVO4) and manipulated its quantum states via a combination of optical and microwave fields. The team then used the Yb
qubit to control the nuclear spin states of multiple surrounding vanadium
atoms in the crystal.

"Based on our previous work, single ytterbium ions were known to be
excellent candidates for optical quantum networks, but we needed to
link them with additional atoms. We demonstrate that in this work,"
says Faraon, the co- corresponding author of the Nature paper.

The device was fabricated at the Kavli Nanoscience Institute at Caltech,
and then tested at very low temperatures in Faraon's lab.

A new technique to utilize entangled nuclear spins as a quantum memory
was inspired by methods used in nuclear magnetic resonance (NMR).



==========================================================================
"To store quantum information in nuclear spins, we developed new
techniques similar to those employed in NMR machines used in hospitals,"
says Joonhee Choi, a postdoctoral fellow at Caltech and co-corresponding
author of the paper. "The main challenge was to adapt existing techniques
to work in the absence of a magnetic field." A unique feature of this
system is the pre-determined placement of vanadium atoms around the
ytterbium qubit as prescribed by the crystal lattice. Every qubit the
team measured had an identical memory register, meaning it would store
the same information.

"The ability to build a technology reproducibly and reliably is key to
its success," says graduate student Andrei Ruskuc, first author of the
paper. "In the scientific context, this let us gain unprecedented insight
into microscopic interactions between ytterbium qubits and the vanadium
atoms in their environment." This research is part of a broader effort
by Faraon's lab to lay the foundation for future quantum networks.

Quantum networks would connect quantum computers through a system that
operates at a quantum, rather than classical, level. In theory, quantum computers w one day be able to perform certain functions faster than
classical computers by taking advantage of the special properties of
quantum mechanics, including superposition, which allows quantum bits
to store information as a 1 and a 0 simultaneously.

As they can with classical computers, engineers would like to be able
to connect multiple quantum computers to share data and work together
-- creating a "quantum internet." This would open the door to several applications, including the ability to solve computations that are
too large to be handled by a single quantum computer, as well as
the establishment of unbreakably secure communications using quantum cryptography.

The paper is titled "Nuclear spin-wave quantum register for a solid-state qubit." Co-authors include graduate students Chun-Ju Wu and Jake Rochman
(MS '19). This research was funded by the Institute of Quantum Information
and Matter (IQIM), a National Science Foundation Physics Frontiers
Center, with support from the Gordon and Betty Moore Foundation, the
Office of Naval Research, the Air Force Office of Scientific Research,
Northrop Grumman, General Atomics, and the Weston Havens Foundation.

========================================================================== Story Source: Materials provided by
California_Institute_of_Technology. Original written by Robert
Perkins. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Andrei Ruskuc, Chun-Ju Wu, Jake Rochman, Joonhee Choi, Andrei
Faraon.

Nuclear spin-wave quantum register for a solid-state qubit. Nature,
2022; 602 (7897): 408 DOI: 10.1038/s41586-021-04293-6 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220217141249.htm

--- up 10 weeks, 5 days, 7 hours, 13 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)