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.