ph.d. student: alessio avella tutor unito: prof. mauro...

Ph.D. Student: Alessio Avella

Tutor Unito: Prof. Mauro Anselmino

Tutor INRiM: Dott. Marco Genovese

Graduate School on Physics and Astrophysics XXVI cicle

Introduction

18-Feb-13 Alessio Avella 2

Introduction

Quantum Cryptography

Quantum Metrology Quantum Information

Foundation of Quantum Meccanics

Quantum Imaging


Absolute calibration technique for photon number resolving detectors


Integrated optical device

Measurement

Quantum states generation

Photon sources

Photon detectors

Quantum states

generation

Quantum state manipulation

Quantum state

measurement

Quantum memory

Introduction

Self consistent, absolute calibration technique for photon number resolving detectors.

Measurement of high degree of entanglement and nonlocality of a two-photon state.

Engeeniring and measurement of spectral property of two-photon states.

Homodyne detection and application to experiment about foundation of quantum meccanics.




A. Avella, G. Brida, I. P. Degiovanni, M. Genovese, M. Gramegna, L. Lolli, E. Monticone, C. Portesi, M. Rajteri, M. L. Rastello, E. Taralli, P. Traina, and M. White.



Single Photon Avalance Diode (SPAD)

Transition Edge Sensor (TES)

Photomultiplier tube

The ideal detector should fulfill the following requirements:

• high quantum detection efficiency over a

large spectral range. • small probability of generating noise. • small jitter. • short dead time.

The ideal detector should fulfill the following requirements: • high quantum detection efficiency over a large spectral range. • small probability of generating noise. • the time between detection of a photon and generation of an electrical signal should be as constant as possible, i.e., the time jitter should be small, to ensure good timing resolution, • the recovery time (i.e., the dead time) should be short to allow high data rates.




Geiger Mode:

Active quenching

Problem: • Afterpulsing • Dark Counts

Si - detector quantum efficiency Some commercial SPAD

InGaAs - detector quantum efficiency



Single Photon Avalance Diode (SPAD) Transition Edge Sensor (TES)

Photon number resolving High quantum efficiency ~ 99% Dead time: ~ 1 μ𝑠 Jitter time: ~ 100 ns Tens mK operating temperature Large dimensions

Not photon number resolving Low quantum efficiency < 60% Dead time: 30 ns – 10 ms Jitter time: 500 ps – 40 ps Room operating temperature Little dimensions

Introduction


Single photons on demand

Heralded single photons

Thermal light Choerent light

Introduction


Hanbury-Brown–Twiss experiment

Classical light

Quantum light


Hamiltonian




𝑘0 = 𝜂0(𝜃0, 𝜙0)𝜔0𝑐 𝑠

𝑘𝑠 = 𝜂𝑠(𝜃𝑠, 𝜙𝑠 )𝜔𝑠𝑐 𝑠

𝑘𝑖 = 𝜂𝑖(𝜃𝑖 , 𝜙𝑖 )𝜔𝑖𝑐 𝑠

Type I:

Tipe II:


Photon source parameters: o Pulse length: 50 ns

o Repetition rate: 20 kHz

o Pump power: 100mW

o Pump wavelength: 404 nm

o Signal wavelength: 808 nm

o Idler wavelength: 808 nm

o NLC: type I, Beta Barium Borate (BBO) , 1mm lenght



In absence of heralded photon:

Measures

In the presence of heralded photons

P(i) P (i)

ξ is the probability of having a true heralding count γ is the TES “total” quantum efficiency




absence of the heralded photon

presence of the heralded photon

Separable Schmidt modes of a non-separable state– Introduction

Separable Schmidt modes of a non-separable state


Alessio Avella, Giorgio Brida, Maria Chekhova, Marco Genovese, Marco Gramegna and Alexander Shurupov.

Separable Schmidt modes of a non-separable state – Introduction


Classical Information

Bit:

Quantum Information

Qubit:

Bloch sphere

Multiple qubit

Be

ll’s

stat

es



Phase space Frequency space

Separable Schmidt modes of a non-separable state – Theoretical aspect

|𝜓 = 𝑑𝜔𝑠 𝑑𝜔𝑖 𝐹 𝜔𝑠, 𝜔𝑖 𝑎𝑠† 𝜔𝑠 𝑎𝑖

† 𝜔𝑖 |𝑣𝑎𝑐

Two-photon state generated by SPDC from a short-pulsed pump:

The Two-Photon Spectral Amplitude (TPSA):

𝐹 𝜔𝑠, 𝜔𝑖 = |𝜓(𝜔0, 𝜔𝑠, 𝜔𝑖)|2𝐹0(𝜔0)

Pump spectrum: 𝐹 𝜔0 Phase matching function: 𝜓(𝜔0, 𝜔𝑠, 𝜔𝑖)




Non factorizable TPSA Schmidt decomposition

Schmidt mode

Where:

Schmidt number Schmidt mode do not overlap in frequency

Separable Schmidt modes of a non-separable state – Experimental aspect

TPSA:

𝐹 𝜔𝑠, 𝜔𝑖 = |𝜓(𝜔0, 𝜔𝑠, 𝜔𝑖)|2𝐹0(𝜔0)

𝑘0 = 𝜂0(𝜃0, 𝜙0)𝜔0𝑐 𝑠

𝑘𝑠 = 𝜂𝑠(𝜃𝑠, 𝜙𝑠 )𝜔𝑠𝑐 𝑠

𝑘𝑖 = 𝜂𝑖(𝜃𝑖 , 𝜙𝑖 )𝜔𝑖𝑐 𝑠

Shaping pump spectrum 𝐹 𝜔0 : Setting crystal parameter: length , material, angles.



Registering the distribution of coincidences between signal and idler photons as a function of frequencies selected by monocromators.

•Kim, Y.-H. and Grice, W. P., Opt. Lett. 30, 908 (2005). •Wasilewski, W., Wasylczyk, P., Kelenderski, P., Banasek, K., and Radzewicz, C., Opt. Lett. 31, 1130 (2006).


Separable Schmidt modes of a non-separable state– Experimental aspect

Two-Photon Time Amplitude (TPTA): the probability amplitude to register a signal photon at time 𝑡𝑠 and an idler photon at time 𝑡𝑖.

𝜔𝑠 =

𝜔0

2+ Ω𝑠

𝜔𝑖 =𝜔0

2+ Ω𝑖

𝐹 (𝑡𝑠, 𝑡𝑖)∝ 𝑑Ω𝑠𝑑Ω𝑖 𝑒𝑖Ω𝑠𝑡 𝑒𝑖Ω𝑖𝑡𝐹 Ω𝑠, Ω𝑖

TPTA is the 2D Fourier transform of TPSA:

|𝐹 (𝑡𝑠, 𝑡𝑖)| 2



𝐹′ (𝑡𝑠, 𝑡𝑖)∝ 𝑑Ω𝑠𝑑Ω𝑖 𝑒𝑖Ω𝑠𝑡 𝑒𝑖Ω𝑖𝑡𝐹′ Ω𝑠, Ω𝑖

In a dispersive medium (as an optical fiber of length l), each of the photon creation operators acquires a frequency-dependent phase that can be attributed to the TPSA.

𝐹 ′ 𝑡𝑠, 𝑡𝑖 ∝ 𝑒−𝑖

𝑡𝑠2

2𝑘𝑠′′𝑙 −𝑖

𝑡𝑖2

2𝑘𝑖′′𝑙𝐹 Ω𝑠, Ω𝑖

𝑘′′ : second-order derivatives of the dispersion law.

𝐹 Ω𝑠, Ω𝑖 ⟶ 𝐹′ Ω𝑠, Ω𝑖 = 𝐹 Ω𝑠 , Ω𝑖 𝑒−𝑖𝑙 𝑘𝑠

′′Ω𝑠2+𝑘𝑖

′′Ω𝑖2 /2

Ω𝑠 =

𝑡𝑠𝑘𝑠′′𝑙

Ω𝑖 =𝑡𝑖𝑘𝑖′′𝑙

•Baek, S. Y., Kwon, O., and Kim, Y.-H., Phys. Rev. A 78, 013816 (2008). •Brida, G., Caricato, V., Chekhova, M. V., Genovese, M., Gramegna, M., and Iskhakov, T. S Opt. Exp. 18 (12), (2010).



Profile FWHM: 0.2 ns Profile FWHM: 2 nm



Laser: mode-locking Ti-Sapphire, pulse's length: 100 fs, gaussian spectrum @ 800 nm bandwidth: 11 nm.

SHG: travelling wave Second Harmonic Generator, gaussian spectrum @ 400 nm bandwidth: 2.8 nm

Fabry-Perot Interferometer: air spacing of 100 μm

Non-linear Crystal: BBO or KDP crystals.

DM: dicroic mirror.

PBS: polarizing beam splitter.

Fiber: 1 km length, single mode , attenuation:<3,5dB=km@780nm.

SPAD: silicon based Single Photon Avalanche Diode, dead time: 78 ns, timing resolution 50 ps, quantum eciency at 800 nm: 15%.


Separable Schmidt modes of a non-separable state – Results

BBO crystal Size: (5x5x10)mm collinear configuration θ0 = 42,4 deg.

KDP crystal Size: (10x10x10)mm collinear configuration θ0 = 67,8 deg.

Pump spectrum

Pump spectrum


Theoretical TPSA

Measured TPSA

Separable Schmidt modes of a non-separable state – Conclusion

Developed a software to calculate spectral property of a two-photon

states.

Made a technique to engeneer the spectral property of a two-photon states.

Made a technique to measure the spectral property of a two-photon

states. Made some measure of TPSA of different states and compare them whit

theoretial prediction.

Made entangled state whit Discrete Schmidt modes in continuous variables.


High degree of entanglement and non-locality – Introduction

High degree of entanglement and non-locality of a two-photon state


F. Sciarrino, G. Vallone, G. Milani, A. Avella 1,2, J. Galinis, R. Machulka, A. M. Perego, K. Y. Spasibko, A. Allevi, M. Bondani and P. Mataloni 1) Istituto Nazionale di Ricerca Metrologica, Torino, Italy; 2) Dipartimento di Fisica, Universita degli Studi di Torino, Torino, Italy;


A. Einstein, B. Podolsky, and N. Rosen, “Can quantum-mechanical description of physical reality be considered complete?” Phys. Rev. 47 777 (1935).



“On the Einstein Podolsky Rosen paradox”, J. S. Bell, Physics 1 195 (1965).

J. S. Bell

He providing a mathematical formulation of locality and realism and he showed specific cases where this would be inconsistent with the predictions of QM.

Bell’s inequalities concern measurements made by observers on pairs of particles that have interacted and then separated.

Many experiment violate Bell’s inequalities but no final test was done

Local hidden variable theory


High degree of entanglement and non-locality – Theoretical aspect

CHSH Inequality

Local

Real

Complete two particles, two observers, Alice and Bob,

and two dichotomic observables


High degree of entanglement and non-locality – Theoretical aspect

measured probabilities:

set of 16 projection measurements:


High degree of entanglement and non-locality – Experiment


High degree of entanglement and non-locality – Results




we obtained CHSH inequality violation by more than 33 standard deviations.

High degree of entanglement and non-locality – Conclusion

Experiment using entangled photons.

Experiment using entangled atoms.

Close detection loophole

Spatial separation

Bell’s inequality violated

Close detection loophole

Spatial separation

Bell’s inequality violated

It is possible exclude HVT???


Large violation of Bell inequalities – Introduction

Alessio Avella 1,2, Giorgio Brida 2, Marco Genovese 1, Marco Gramegna 1. 1) Istituto Nazionale di Ricerca Metrologica, Torino, Italy; 2) Dipartimento di Fisica, Universita degli Studi di Torino, Torino, Italy;

Violation of Bell’s inequality using Both continuous and discrete variable


Large violation of Bell inequalities – Theoretical aspect

Fock rapresentation: Quadrature rapresentation:


Large violation of Bell inequalities – Experiment



With θ = 0 With θ = π/2



X measurement

N measurement

N > 0 a, b = −1

N = 0 a, b = 1

a, b = −1 a, b = 1 a, b = −1

-z z


Conclusion


Measurement of high degree of entanglement and nonlocality of a two-photon state.

Separable Schmidt modes of a non-separable state

Homodyne detection and application to experiment about foundation of quantum meccanics.


Conclusion

“Engineering of spectral properties of two-photon states”, poster presented at the conference “Inaugural Workshop on Quantum-Photonic Hardware” (Perth, Australia, 22-25 October 2012).

“Engineering of spectral properties of two-photon states”, contributed talk at the conference “IQIS 2012” (Padova, Italy, 26-28 September 2012).

“Engineering of spectral properties of two-photon states”, poster presented at the conference “Quantum 2012” (Torino, Italy, 20-26 May 2012).

“Engineering of spectral properties of two-photon states”, poster presented at the conference “SPIE Optical Engineering + Applications” (San Diego, United States, 12-16 August 2012).

Engineering of spectral properties of two-photon states”, contributed talk at the conference “Quantum Africa 2” (South Africa, 3-7 September 2012).


Conclusion

• A. Avella, G. Brida, M. Chekhova, M. Genovese, M. Gramegna, M. Vieille-Grosjean, A. Shurupov; “Engineering of spectral properties of two-photon states, preliminary results” Proc. SPIE 8518, Quantum Communications and Quantum Imaging X, 851812 (2012).

• F. Sciarrino, G. Vallone, G. Milani, A. Avella, J. Galinis, R. Machulka, A. M. Perego, K. Y. Spasibko, A. Allevi, M. Bondani and P. Mataloni, "High degree of entanglement and nonlocality of a two-photon state generated at 532 nm" EPJ-ST 199, number 1 (2011).

• A. Avella, G. Brida, I. P. Degiovanni, M. Genovese, M. Gramegna, L. Lolli, E. Monticone, C. Portesi, M. Rajteri, M. L. Rastello, E. Taralli, P. Traina, and M. White, “Self consistent, absolute calibration technique for photon number resolving detectors," Opt. Express 19, 23249-23257 (2011).


A. Avella, G. Brida, D. Carpentras, A. Cavanna, I. P. Degiovanni, et al. "Report on proof-of-principle implementations of novel QKD schemes performed at INRIM", Proc. SPIE 8542, Electro-Optical Remote Sensing, Photonic Technologies, and Applications VI, 85421N (2012). A. Avella, G. Brida, D. Carpentras, A. Cavanna, I.P. Degiovanni, M. Genovese, M. Gramegna, P. Traina; “Review on recent groundbreaking experiments on quantum communication with orthogonal states”, preprint arXiv:1206.1503 (2012). A. Avella, G. Brida, I. P. Degiovanni, M. Genovese, M. Gramegna, and P. Traina, “Experimental realization of Goldenberg — Vaidman QKD protocol”. Applied Sciences in Biomedical and Communication Technologies (ISABEL), 2010 3rd International Symposium on, 10.1109/ISABEL.2010.5702879 (2010). A. Avella, G. Brida, I.P. Degiovanni, M. Genovese, M. Gramegna, P. Traina; “Experimental quantum-cryptography scheme based on orthogonal states” Physical Review A 82 (6), 062309 (2010). A. Avella, G. Brida, I. P. Degiovanni, M. Genovese, M. Gramegna and P. Traina, "Experimental quantum cryptography scheme based on orthogonal states: preliminary results". Proc. SPIE 7702, 77020E (2010).

ph.d. student: alessio avella tutor unito: prof. mauro...

Documents