Page 14 - Summer 2025

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improved energy efficiency, simplification of chip
design, and application of higher qubit density.
One of the leaders of the study, PhD researcher Joe
Carroll, comments:
“ Traditionally researchers have searched
for topological superconductors by taking
measurements using metallic probes. What’s
new about our technique is that we use another
superconductor to probe the surface of uranium
ditelluride. By doing so we exclude the normal
surface electrons from our measurement, leaving
behind only Majorana fermions”.
Reference: West, P., Electronic Specifier, 30th. June is able to simulate quantum computations that
World First Method of error-correctable
Quantum Computers Simulation
Researchers at Chalmers University of Technology
in Sweden, the University of Milan, the University of
Granada and the University of Tokyo have revealed
a method for simulating specific types of error-
corrected quantum computations, marking a
significant advance in quantum technology.
In order to verify the accuracy of a quantum
computation the calculations are simulated using
conventional computers, and one particularly
important type of quantum computation that is of
interest is the type that can withstand disturbances
and effectively correct errors. The immense
complexity of quantum computations, however,
makes simulation especially difficult.
Now, a method has been devised for accurately
simulating a certain type of quantum computation
that is particularly suitable for error correction, but
which so far has been extremely difficult to simulate. Professor of Applied Quantum Physics at Chalmers
The hitherto limited ability of quantum computers
to implement error correction is a function of their
fundamental building block i.e. the qubit. Qubits have
immense computational power, but are also highly
sensitive and therefore susceptible to disturbance.
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In order to counteract this susceptibility error
correction codes are introduced to distribute
information across multiple subsystems so as to
allow errors to be detected and corrected without
destroying the quantum information. One way of
doing this is to encode the quantum information of a
qubit into the multiple or possibly even infinite energy
levels of a vibrating quantum mechanical system, a
method known as bosonic coding. Until now, however,
this method has been prone to unreliability due to the
multiple energy levels, which are difficult to simulate
with conventional computers.
With the new method an algorithm is used that
use a specific kind of bosonic code known as the
Gottesman-Kitaev-Preskil, or GKP, code. This is
commonly used in leading implementations of
quantum computers and the team was able to
use the code in their algorithm by creating a new
mathematical tool.
Cameron Calcluth, First Author of the study, states:
“We have discovered a way to simulate a specific
type of quantum computation where previous
methods have not been effective. This means that
we can now simulate quantum computations with
an error correction code used for fault tolerance,
which is crucial for being able to build better and
more robust quantum computers in the future.
The slightest noise from the surroundings in the
form of vibrations, electromagnetic radiation, or
a change in temperature can cause the qubits
to miscalculate or even lose their quantum state,
their coherence, thereby losing their capacity to
continue calculating”.
Co-author of the study, Giulia Ferrini, Associate
University, adds:
“The way it [the GKP Code] stores quantum
information makes it easier for quantum
computers to correct errors, which in turn makes
them less sensitive to noise and disturbances. Due
to their deeply quantum mechanical nature, GKP
Codes have been extremely difficult to simulate
using conventional computers. But now we have
finally found a unique way to do this much more
effectively than with previous methods.
This opens up entirely new ways of simulating
quantum computations that we have previously
been unable to test but are crucial for being able to
build stable and scalable quantum computers”.
Reference: Miles, S., Electronic Specifier, 3rd. July
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RECONFIGURABLE
OPTICAL DEVICE FOR
LIGHT-BASED COMPUTING
Engineers at the John and Marcia Price College
of Engineering have pioneered the development
of a new device that can dynamically control
the circular polarisation of light, a property that
enables the encoding and storage of information,
offering a pathway towards more compact and
efficient optical circuits.
The new device has been likened to “living optical
matter” which responds in real-time to electrical
pulses. At its heart is a carefully engineered
heterostructure that is composed of multiple stacked
thin films, including a layer of carbon nanotubes
aligned in varying directions which serve the dual
functions of manipulating the ‘chirality’ of light and
the conduction of electrical signals. These signals
trigger a phase-change material (PCM) layer to
transition between amorphous and crystalline states.
This structural change affects the degree to which
the material absorbs left or right circularly polarised
light, known as circular dichroism. This property
was able to be finely controlled across a full wafer
following improvements in the scalable fabrication
of both the aligned carbon nanotubes and the PCM
layers.
Once integrated the heterostructure selectively
filters circularly polarised light depending on the
state of the PCM. Crucially, this process is reversible switching - eliminating the need for separate control
and electrically tuneable, allowing real-time control components”.
over the optical behaviour of the device. This
opens the door to encoding information based on Assistant Professor Weilu Gao of the Department of
the “handedness” (left or right) of polarised light, Electrical and Computer Engineering adds:
potentially creating new channels for optical memory
“ Traditional chiral optics were like carved stone
and computation.
- beautiful but frozen. This made them not useful
for applications requiring real-time control, like
PhD student Jichao Fan comments:
reconfigurable optical computing or adaptive
“ We’ve created ‘living’ optical matter that evolves sensors.
with electrical pulses, thanks to our aligned-
By adding circular dichroism as an independent
carbon-nanotube-phase-change-material
parameter, we create an orthogonal information
heterostructure that merges light manipulation
channel. Adjusting it does not interfere with other
and memory into a single scalable platform.
properties like amplitude or wavelength”.
The carbon nanotubes simultaneously act as chiral
Reference: West, P., ‘Researchers create reconfigurable Optical
optical elements and transparent electrodes for PCM Device for Light-based Computing’, Electronic Specifier, 7th. July
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