Before quantum
information sciences and quantum computing can revolutionize tasks ranging from
chemistry and pharmaceutical design to sensing and decryption, scientists need
a better way to manipulate the critical elements of a quantum computer — known
as quantum bits, or qubits — and their control components.
Currently, this
process must take place outside of the low-temperature environment that
superconducting quantum computers need, meaning every control and readout
component must run microwave signals out of and back into a refrigerator —
which can add time, cost and complexity to an already complicated operation.
But scientists at the Johns Hopkins University Applied Physics Laboratory (APL)
in Laurel, MD, have developed a new device for controlling and measuring qubits
inside the cooler environment; the new device can be manipulated at lower
frequency, without the need for microwave lines, thus reducing cost and
complexity.
The researchers describe the tool in “Tunable Superconducting Cavity using Superconducting Quantum Interference Device Metamaterials,” published recently in Scientific Reports, JHU APL announced April 24.
Their paper shows
the design and modeling of a new type of tunable, microwave cavity tailored for
quantum computing and quantum information experiments. The device consists of a
metamaterial — a material made up of large artificial atoms — composed of an
array of superconducting quantum interference devices (SQUIDs) that allow users
to tune the properties of the cavity by applying a small magnetic field to the
artificial atoms.
“This changes [the
atoms’] properties, which in turn changes the properties of the cavity,”
explained lead author David Shrekenhamer, a metamaterials expert in APL’s
Research and Exploratory Development Department. “Cavities in microwave
electronics act as signal filters, and in quantum computing applications they
enable the coupling to single qubits. This means we’ve developed a new way to
tune electronics in a quantum computer, allowing for novel ways to control
qubits, filters and couplings between control signals and qubits.”
All of this can be
done inside of a dilution refrigerator that is 20 thousandths of a degree above
absolute zero, where traditional ways of doing this aren’t possible. “It’s an
entirely new approach to device control that will be an important piece of
scaling quantum computer systems to the larger sizes needed for more complex
applications,” Shrekenhamer added.
Source: JHU APL
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