Think Small, Bath & Bristol Enterprise Network, 20 Apr 2010

Integrated quantum photonicsJeremy O’Brien

NEDQITNEDQIT

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Think Small, Bath & Bristol Enterprise Network, 20 Apr 2010

Quantum technologiesPhotonic approachQuantum circuits on silicon chips

Think Small, Bath & Bristol Enterprise Network, 20 Apr 2010

Physical is quantum Quantum information

No physical representation No information

No physical process No processing

Revolution in information and communication technologies

“Information is physical” - Rolf Landauer

Think Small, Bath & Bristol Enterprise Network, 20 Apr 2010

Quantum mechanics

A description of the world at small scales

Quantized

Inherently uncertaineg. position-momentum ‘uncertainty principle’

Very counter intuitive

…and very useful

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Normal bit quantum bit or ‘qubit’:

a two-level quantum mechanical system

eg. the polarisation of a single photon:

‘Superposition’

+0 1

Quantum information

JL O’Brien Science, 318, 5856 (2007)

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Entanglement

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Entanglement is “the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought.”- Schrödinger, 1935

Entanglement

…

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Communication

Lithography

JL O’Brien, A Furusawa, J Vuckovic Nature Photonics, 3, 687 (2009)

Security based on Physics

Ladd, et al Nature 464, 45 (2010)

Computation

Tremendous power

MetrologyPrecision measurement

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9

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Encoding Quantum Information in Photons

JL O’Brien Science, 318, 5856 (2007)

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2-photon interactions?

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Think Small, Bath & Bristol Enterprise Network, 20 Apr 2010

Photonic Controlled-NOT gate

Control

Target

IN OUT

00 00

01 01

10 11

11 10

Milburn, PRL 62, 2124 (1989)

0

1Control

Target0

1

Non-linearphase shift

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Think Small, Bath & Bristol Enterprise Network, 20 Apr 2010

Quantum information with photons

Knill, Laflamme and Milburn Nature 409, 46 (2001)

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Non-classical interference

50% BS

P = P( ) + P( )x

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P = | + |2

Non-classical interference

12. 12 i

2. i2

2

050% BS

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Information processing

Lanyon et al. Nature Physics 5 134 (2009)O’Brien, et al., Nature 426 264 (2003)

O’Brien, Science, 318 5856 (2007)

Communication

Clark, Fulconis, Rarity, Wadsworth, O’Brien Phys. Rev. A 79 030303 (2009)

Nagata, Okamoto, O’Brien, Sasaki, TakeuchiScience, 316 726 (2007); NJP 10 073033 (2008)

MetrologyEntanglement

Okamoto, O’Brien, Hofmann, Nagata, Sasaki, Takeuchi Science, 323 483 (2009)

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Think Small, Bath & Bristol Enterprise Network, 20 Apr 2010

~25 mm

Politi, Cryan, Rarity, Yu, and O’Brien Science, 320, 5876 (2008)

Integrated quantum photonics

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CNOT gate on a chip

Laing, Peruzzo, Politi, Rodas Verde, Halder, Ralph, Thompson, O’Brien arXiv:1004.0326

Ideal: Expected: Measured:

F = 0.969 ± 0.002S = 0.993 ± 0.002

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Manipulation of Entanglement on a chip

Matthews, Politi, Stefanov, and O’BrienNature Photonics 3, 346 (2009)

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Quantum factoring algorithm on a chip

Politi, Matthews, O’Brien Science 325 1221 (2009)

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Quantum factoring algorithm on a chip

Politi, Matthews, O’Brien Science 325 1221 (2009)

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Quantum walks in SiOxNy

Peruzzo, Matsuda, Matthews, Politi, Poulios, Lobino, Zhou, Wórhoff, Bromberg, Lahini, Silberberg, Thompson, O’Brien

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Two- particle quantum walks

Peruzzo, Matsuda, Matthews, Politi, Poulios, Lobino, Zhou, Wórhoff, Bromberg, Lahini, Silberberg, Thompson, O’Brien

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Conclusions

Quantum Communication& Computing

Reconfigurable circuits& Precision measurement

Quantum simulations+Sources & Detectors