Page 15 - Summer 2025

Industry News

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