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of qubits, and much needed for the successful World’s first Fault-Tolerant Quantum Computer
commercialisation of quantum computers.
The world’s first commercial fault-tolerant
Silicon quantum dots, with diameters in the tens computer equipped with so-called ‘logical
of nanometres, have the advantage of being qubits’ is expected to be operational later this
compatible with existing silicon fabrication year.
technologies, but it has hitherto been difficult
to connect quantum dots that are not in close Logical qubits, that is physical quantum bits
proximity. In order to connect many qubits they interconnected through quantum entanglement,
have to be densely crammed into a very small enhance the accuracy of quantum computing by
area, and using wires to connect such densely duplicating data storage across several locations,
packed qubits is not practical. which diversifies the points of failure during
computations, mitigating error risks.
The RIKEN team has therefore devised a two-qubit
The quantum computer that has been created, by
logic gate between silicon spin qubits that are
QuEra in collaboration with Harvard University, has
physically apart, a development that opens the
256 physical qubits and ten logical qubits, and is
door to scaling up quantum computing based on
said to lay the groundwork for software developers
silicon quantum dots.
to commence experimentation with code for
The technique, known as spin shuttling, enables future quantum computing iterations.
the movement of single spin qubits across a
quantum dot array without disrupting their phase The need for error correction in quantum
coherence (vital for quantum computers as it computing stems from its use of qubits, which,
transports information ). It involves propelling unlike conventional computers that use bits that
electrons through an array of qubits by applying a are either 0 or 1, can exist in a superposition of
voltage. states between 0 and 1. Quantum entanglement
enables qubits to be interconnected, facilitating
With coherent spin shuttling quantum information, simultaneous existence in multiple states so
specifically the spin state of a particle, is calculations can be achieved at much higher
transferred between different locations without speeds than with conventional computers.
losing its quantum coherence ( the property that Unfortunately, however, qubits are prone to
allows particles to be in a combination of states at disturbances, which cause a high error rate.
the same time ). Around one in a thousand qubits have a tendency
to fail, as against one in a billion billion bits in
Reference: Fowle, H., Electronic Specifier, 15th. January traditional computers.
By utilising data redundancy, where identical
Reaching the Ground State of Quantum Sound
information is stored in multiple locations, logical
qubits serve to reduce error rates should physical
Scientists at the Max Planck Institute for the
qubits fail, so ensuring that calculations can
Science of Light have successfully cooled sound
continue without disruption.
waves in optical fibres using laser light, bringing
the achievement of the highly desired quantum
In order to create the logical qubits, error-
ground state of sound in waveguides ever closer.
correcting computer code is applied to regular
qubits, and logical gates or circuits introduced to
Quantum ground state is a state with minimal
create the entanglement. The quantum computer
energy and disturbance, and by cooling the
then calculates the ‘syndrome’ ( an indicator of
system scientists aim to reduce acoustic phonons
potential errors ) and corrects any detected errors
( particles of sound that can disrupt quantum
before moving on to the next operational phase.
measurements ) to virtually zero, so bridging the
gap between classical and quantum mechanics
[ Reference: Fowle, H., Electronic Specifier, 20th. February ]
and enhancing the precision of quantum
observations.
The study, led by Dr. Birgit Stiller, reports a
significant reduction in temperature of a sound Visit our website!
wave, initially at room temperature, by 219 Kelvin Why not head down to our website
using laser cooling. This method, ten times more and read more news in our blog?
effective that previous methods, reduced the initial Updated daily with hand-picked
articles from around the web...
phonon number by 75 per cent, achieving a low
temperature of 74 Kelvin (minus 194 Celsius).
institutionofelectronics.ac.uk
Reference: Fowle, H., Electronic Specifier, 24th. January
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