Quantum radiometry research activities at NRC

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Quantum radiometry research activities at NRC

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Quantum Radiometry Research at NRC

Measurement Science and Standards

Jeff Lundeen, Research Officer

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•

1

1 lightbulb

lightbulb

= 10 billion

billion

photons/s

•

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CORM 2012 – Quantum Radiometry

•

• Single Photon Detectors for increased range

Single Photon Detectors for increased range

•

• Single Photons to reach the bandwidth limit

Single Photons to reach the bandwidth limit

•

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L

aser

I

nterferometer

G

ravitational-Wave

O

bservatory

•

• Quantum Metrology establishes the

Quantum Metrology establishes the

fundamental limits of measurement

•

• Quantum Light allows us to reach

Quantum Light allows us to reach

these limits

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•

• Imaging sensitivity and resolution is

Imaging sensitivity and resolution is

limited by the photonic nature of light

•

• Single Photon Sensitive Cameras are

Single Photon Sensitive Cameras are

being used in Astronomy and Microscopy

1/1000 photons/pixel

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• Absolute calibration of detector efficiency

with quantum light

• Absolute brightness sources based on

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Andreas Fiore, Nature Photonics 2, 302 - 306 (2008)

Silicon Photomuliplier Arrays

Electron Multiplying CCDs Superconducting Nanowire Arrays

Single Photon Detectors

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Top View

Side View

Superconducting Nanowire Single Photon Detectors

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How Superconducting Detectors Work

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Avalanche Photodiode Single Photon Detectors

• In Gieger mode, the avalanche in APDs creates a milliamp current pulse for every photon

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Single Photon Generation

Momentum is conserved..

..as well as energy

ϕ_PUMP= ϕ_s + ϕ_i k_s k_i k_PUMP Downconversion • A pump photon is spontaneously converted into two lower frequency photons in a material with a nonzero χ(2) ω_PUMP ωs ω_i ∝ 2π/L Pump s i |1〉 Pump s i

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P

u

ls

e

d

L

a

s

e

r

Femtosecond Pulse Generation

Photon Pair Detection

Blue Generation

Photon Pair Production

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CORM 2012 – Quantum Radiometry S im u lt a n e o u s C lic k s /s Time bins 12 ns

Evidence for Photon Pairs

Laser pulse separation Random

coincident clicks Correlated Photon Pairs

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Absolute Detector Efficiency Calibration

The problem: How do you determine the efficiency of a given optical detector?

The standard solution: Use a light beam of previously calibrated brightness (i.e. # of photons) and count the # of electrons produced.

The limitation: Errors in brightness calibration directly translate into errors in efficiency calibration (and vice versa).

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Efficiency: Klyshko’s Method

Use the photon pairs produced in SPDC and two photon detectors to measure the efficiency

D. N. Klyshko, “Use of two-photon light for absolute calibration of photoelectric detectors,” Sov. J. Quantum Electron. 10, 1112–1117 (1980). Coincidence Rate i s

R

∩ s

R

i

R

AND i s

P

∩ Pair Production Rate Rate of clicks Rate of clicks i

η

s

η

i s s s

P

R

∩

⋅

=

η

i s s i i s

P

R

∩ ∩

=

η

⋅

η

⋅

÷

=

i s i s

R

η

=

∩

η

The brightness drops out of the efficiency equation The other detector’s efficiency also drops out

i s

P

∩ s

η

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Joint Click Statistics

Pump Pulse Energy=6 J Pump Pulse Energy=120 J

We find that that are 96% of the time the photon number is N i N i N s Ns

• A weak test of the optimum: After finding the optimal efficiencies ηi

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Results and Comparison

Proof-of-Principle experiment

Variation in reconstructed efficiencies across pump powers: 0.4% (st. dev.)

Breakdown for Klyshko Method as soon as higher photon numbers become significant

Constant efficiency, if complete joint statistics are considered

Contamination from background

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SiO₂ InP

InAs

Quantum Dot Sources of Single Photons

• InP pyramids are grown on square templates.

• The top of the pyramids is 30nm x 30nm – room for only one dot.

• Single quantum dots are optically pumped to deterministically produce telecom single photons at high

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(a)

Advantages of site-selected quantum dots

• Since the position of the dots is known to within 20nm, other structures can be grown

around them.

• Electrical Gates for Stark shifting of the dot energy levels.

• Photonic Bandgap Defect

Cavities to enhance emission into one optical mode.

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