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New chip technology paves way for better quantum computing power

New chip technology paves way for better quantum computing power

According
to a press release by the University
of Bristol
in the UK, an international team of quantum scientists and
engineers have realised an advanced large-scale silicon quantum photonic device
that can entangle photons to incredible levels of precision.

The
work was in collaboration with Peking University, Technical University of
Denmark (DTU), Institut de Ciencies Fotoniques (ICFO), Max Planck Institute,
Center for Theoretical Physics of the Polish Academy of Sciences, and
University of Copenhagen. 

The paper titled “Multidimensional
quantum entanglement with large-scale integrated optics”
has been published
in the journal Science.

The
coherent and precise control of large quantum devices and complex
multidimensional entanglement systems has been a challenging task owing to the
complex interactions of correlated particles in large quantum systems.

Significant
progress towards the realization of large-scale quantum devices has been
recently reported in a variety of platforms including photons, superconductors,
ions, dots and defects. In particular, photonics represents a promising
approach to naturally encode and process multidimensional qudit states in the photon’s
different degrees of freedom.

The
team was led by scientists from the University of Bristol’s Quantum Engineering Technology
Laboratories (QET Labs)
 has demonstrated the first ever large-scale
integrated quantum photonic circuit, which integrating hundreds of essential
components, can generate, control and analyse high-dimensional entanglement
with an unprecedented level of precision.

The mission
of QETLabs is to take quantum science discoveries out of the labs and engineer
them into technologies for the benefit of society.  It brings together £50
million worth of activity that covers theoretical quantum physics through
experiment, engineering and skills and training toward concept demonstrators of
quantum technologies.

According
to the leader of the Bristol team Professor Mark
Thompson
, the team used the same manufacturing tools and techniques that
are exploited in today’s microelectronics industry to realise the silicon
quantum photonic microchip.

 “However, unlike conventional electronic
circuits that utilise the classical behaviour of electrons, the  circuits exploit the quantum properties of
single particle of light. This silicon photonics approach to quantum
technologies provides a clear path to scaling up to the many millions of
components that are ultimately needed for large-scale quantum computing
applications,” Prof Thompson said.

While
standard quantum hardware entangles particles in two states, the team has found
a way to generate and entangle pairs of particles that each has 15 states.

Dr
Anthony Laing
, a lead academic in Bristol’s QETLabs and corresponding
author, said: “Entanglement is a fascinating feature of quantum mechanics and
one that we do not yet fully understand. This device and future generations of
chips of increasing complexity and sophistication will allow us to explore this
realm of quantum science and make new discoveries.”

In
this work, a programmable path-encoded multidimensional entangled system with
dimension up to 15×15 is demonstrated, where two photon exists over 15 optical
paths at the same time and are entangled with each other.

This
multidimensional entanglement is realised by exploiting silicon-photonics
quantum circuits, integrating in a single chip, 550 optical components,
including 16 identical photon-pair sources, 93 optical phase-shifters, 122
beam-splitters.

“It
is the maturity of today’s silicon-photonics that allows us to scale up the
technology and reach a large-scale integration of quantum circuits,” said Lead
author Dr
Jianwei Wang
.

The
integrated photonic chip sets a new standard for complexity and precision of
quantum photonics, with immediate applications for quantum technologies.

“Our
quantum chip allows us to reach unprecedented levels of precision and control
of multidimensional entanglement, a key factor in many quantum information
tasks of computing and communication,” Dr Wang added.

Integrated
quantum photonics allows the routing and control of single particles of light
with intrinsically high stability and precision, however to date it has been
limited to small-scale demonstrations in which only a small number of
components are integrated on a chip.

Scaling
up these quantum circuits is of paramount importance to increasing the
complexity and computational power of modern quantum information processing
technologies, opening-up the possibility of many revolutionary applications.

"The
development of powerful large-scale integrated photonic quantum chips will
provide an efficient route to the future applications in the fields of quantum
communication, quantum computing and many others," said Professor Qihuang
Gong
, the lead academic from Peking University.

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