Page 11 - Autumn 2024

First continuously operating Quantum This is the first time that a quantum computer has
Computer successfully executed an algorithm the results of
which have been able to be independently verified
Scientists at Harvard University have built the
and repeated - a major step towards the practical
first ever quantum computer that can operate
deployment of quantum hardware in scientific
continuously without restarting. This is viewed
applications.
as being a breakthrough since most quantum
computers can only run for milliseconds and even
Quantum verification refers to the ability to reproduce
the advanced machines have so far only operated
a result on another quantum system of comparable
for around 13 seconds.
capability, confirming that a computation is both
correct and scalable. This has been a long-standing
challenge owing to the fact that quantum states are
fragile and error-prone.
The Willow chip has an architecture that significantly
reduces quantum error rates and the Quantum
Echoes technique has been likened to sending
a signal to a quantum system then reversing it
to capture a return ‘echo’. This echo is enhanced
by constructive interference between quantum
waves, which provides an exceptionally sensitive
measurement for more accurate and complex
simulations.

A major problem in quantum is the so-called ‘atomic
loss’, where qubits effectively escape from the system
causing it to lose information and ultimately fail. In
order to address this the Harvard team deployed two
tools that can move atoms and subatomic particles,
basically an “optical lattice conveyor belt” and a pair
of “optical tweezers” which act so as to replenish
qubits as they escape. Up to 300,000 atoms per
second can be input to the machine, compensating
for the ‘atomic loss’.

Research Associate Tout T. Wang, who was involved in
designing the machine, comments:
In collaboration with the University of California,
“There’s now fundamentally nothing limiting how long
Berkeley, Google demonstrated how Quantum
our usual atom and quantum computers can run for.
Echoes can be applied notably to chemical research
Even if atoms get lost with a small probability, we can
by analysing the structure of two molecules
bring fresh atoms in to replace them and not affect
containing 15 and 28 atoms respectively. The
the quantum information being stored in the system”.
quantum-derived results matched those of Nuclear
Magnetic Resonance (NMR) measurements as
Reference: ‘Researchers develop continuously operating Quantum
Computer’, New Electronics, Vol.58, Issue 9, October 2025, p.7 well as revealing additional information that is
fundamentally inaccessible with traditional NMR. This
proof-of-concept experiment therefore pointed to a
Quantum Processor outperforms tool that could reveal molecular and atomic-scale
Supercomputers by 13,000 Times phenomena that is currently beyond the reach of
existing instruments.
A new algorithm known as Quantum Echoes, which
ran on Google’s Willow quantum chip, has allowed Ashok Ajoy, Assistant Professor of Chemistry at UC
researchers to model the structure of physical Berkeley, states:
systems ranging from molecules to magnetic
“Google’s Quantum Echoes algorithm showcases
materials and black holes.
the potential for quantum computers to efficiently
model and unravel these spins, possibly even

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