Researchers in National
Physical Laboratory (NPL)’s Quantum Detection Group have demonstrated, for the
first time, a monolithic 3D ion microtrap array which could be scaled up to
handle several tens of ion-based quantum bits (qubits). The research, published
in Nature Nanotechnology, shows how it is possible to realize this
device embedded in a semiconductor chip, and demonstrates the device’s ability
to confine individual ions at the nanoscale.
As the U.K.’s National Measurement Institute, NPL is
interested in how exotic quantum states of matter can be used to make high-precision
measurements of, for example, time and frequency, ever more accurate. This
research, however, has implications wider than measurement. The device could be
used in quantum computation, where entangled qubits are used to execute
powerful quantum algorithms. As an example, factorization of large numbers by a
quantum algorithm is dramatically faster than with a classical algorithm.
Scalable ion traps consisting of a 2D array of electrodes
have been developed, however 3D trap geometries can provide a superior
potential for confining the ions. Creating a successful scalable 3D ion
trapping device is based on maintaining two qualities—the ability to scale the
device to accommodate increasing numbers of atomic particles, whilst preserving
the trapping potential which enables precise control of ions at the atomic
level. Previous research resulted in compromising at least one of these
factors, largely due to limitations in the manufacturing processes.
The team at NPL has now produced the first monolithic ion
microtrap array which uniquely combines a near-ideal 3D geometry with a
scalable fabrication process—a breakthrough in this field. In terms
of elementary operating characteristics, the microtrap chip outperforms
all other scalable devices for ions.
Using a novel process based on conventional semiconductor
fabrication technology, scientists developed the microtrap device from a silica-on-silicon
wafer. The team was able to confine individual and strings of up to 14 ions in
a single segment of the array. The fabrication process should enable device
scaling to handle greatly increased numbers of ions, whilst retaining the
ability to individually control each of them.
Due to the enormous progress in nanotechnology, the power
of classical processor chips has been scaled up according to Moore’s Law.
Quantum processors are in their infancy, and the NPL device is a promising
approach for advancing the scale of such chips for ion-based qubits.
Source: National Physical Laboratory