Generation of ultra-broadband entangled photons from chirped-MgSLT - - PowerPoint PPT Presentation

Generation of ultra-broadband entangled photons from chirped-MgSLT crystal: towards mono-cycle temporal entanglement generation

Akira Tanaka*a,b, Ryo Okamoto a,b, Hwan Hong Lim c, Shanthi Subashchandrana,b, Masayuki Okanoa,b, Labao Zhangd, Lin Kangd, Jian Chend, Peiheng Wud, Toru Hirohatae, Sunao Kurimurac and Shigeki Takeuchia,b

takeuchi@es.hokudai.ac.jp

• a. Research Institute for Electronic Science, Hokkaido University, Japan
• b. The Institute of Scientific and Industrial Research, Osaka University, Japan
• c. National Institute for Materials Science, Japan
• d. Research Institute of Superconductor Electronics, Nanjing University, China
• e. Central Research Laboratory, Hamamatsu Photonics, Japan
• Univ. of Virginia Charlottesville, USA 2013.2.11

About me

• B.S. @ Osaka Univ. (2005.4-2009.3, Prof. N. Imoto’s LAB.)

Thesis: theory on efficient classical simulation of Q.C.

• M.S. @Osaka Univ. (2009.4-2011.3, Prof. S. Takeuchi’s LAB.)

Q-state tomography of tapered fiber-microsphere cavity system

• Opt. Express 19 (3), 2278--2285 (2011)
• Ex. on Parametric Down Conversion and quantum interference

(Prof. S. Takeuchi’s Lab.)

• D.C. @ Osaka Univ. (2011.4- Now, Prof. S. Takeuchi’s LAB.)
• Ex. on ultra-broad PDC using chirped-QPM crystal and its temporal

compression

• Opt. Express 20 (23), 25228--25238 (2011)

Our institutes

Osaka Univ. We work here Hokkaido Univ. Our lab belongs to here

Quantum gates (simplified CNOT, Entanglement filter, KLM-CNOT) & Quantum metrological applications (NOON states) diameter: 178µm

Taper Nano Fiber

Microsphere cavity (Ｑ～107) Diamond Nitrogen Vacancy center Diffraction-limited Light confinement Low Temp. (4K) exciting ZPL of NV

• 1. Quantum Information Processing using Photons.

Our activities

• 2. Manipulating Light Quanta using Nano Technology.

Okamoto Fujiwara Okano Tanida Tanaka Zhao Takeuchi Kasagi Shanthi Sagawa Yokoi Members of Quantum & Advanced optics group 2012, RIES, Hokkaido Univ. & ISIR Osaka Univ. (temporally in Osaka now) Kamioka Oyama Ito Ono Yoshida Eto

Collaborators on this work

• Prof. Sunao Kurimura, NIMS
• Dr. Hwan-Hong Lim, NIMS
• Prof. Peiheng Wu, Nanjing Univ.
• Prof. Jian Chen, Nanjing Univ.
• Dr. Toru Hirohata, Hamamatsu Photonics. K.K.
• 3. Metrological application using Monocycle Entangled Photons

• Monocycle entangled photon source
• Two-photon temporal compression
• Chirped-MgSLT crystals
• Collinear SPDC experiment
• Non-collinear SPDC with two broadband detectors
• Estimates on two-photon temporal widths
• Next step: measuring frequency correlation
• Conclusion

Outline

Monocycle entangled photon source (MEPS)

A state where two photons are correlated in a very short time (a few femtoseconds), only one cycle of light oscillation.

Quantum Optical Coherence Tomography Efficient Two-Photon Absorption Clock Synchronization (Theory) M.B. Nasr et al., PRL91, 083601 (2003)

• B. Dayan et al.,

PRL93, 023005(2004)

• V. Giovannetti et al.,

PRL87, 117902(2001)

< µm resolution MHz resolution fs precision Possible Applications to Quantum Metrology Possible Applications to Quantum Metrology Classical Monocycle Pulses Monocycle Entangled Photons t few fs few fs t Constant Low prob. Broad (~200THz) Random High prob. Narrow (~MHz or smaller) Timing Pair production Energy sum

S.E. Harris, PRL 98, 063602 (2007).

Requirements for monocycle entanglement

ts ti

Ultra-broad (octave span) Ultra-short (~several fs) Frequency domain Time domain

Wave-function of monocycle-entangled photons

νs νi ∆ν

Frequency correlation

∆t

Temporal correlation

Large ∆ν is required to achieve monocycle entanglement. Nonlinear optical crystal CW-laser Worse pair production∝ ∝ ∝ ∝L2 Thin crystal length L Increase ∆ν Method: Parametric down conversion Problem.

Current status towards realizing MEPS

2007 Theoretical proposal S.E. Harris, PRL 98, 063602 (2007). 2008 Non-collinear, ∆λ = 400 nm, 404 nm pump

M.B. Nasr et al., PRL 100, 183601 (2008).

2009 Collinear, ∆λ = 700 nm, 532 nm pump

• N. Mohan et al., Appl. Opt. 48 (20) 4009 (2009).

2010 Preliminary chirp & compress with ∆λ = 40 nm, 532 nm pump

• S. Sensarn et al., PRL 104, 253602 (2010).

2012 (This talk) Non-collinear, ∆λ = 820nm, 532 nm pump Akira Tanaka et al., Opt. Express 20 (23), 25228 (2012). 420nm 420nm Frequency separator

Nonlinear optical crystal

Chirped Quasi-phase-matched (QPM) device Chirped Quasi-phase-matched (QPM) device Idler: 1.0～4.5µm Signal: 0.46～0.75µm MEPS MEPS control Dispersion control 3.11µm 7.02µm Poling periods 0.75&1µm 0.46&4.5µm Generated photons Continuous tuning of ωs&ωi

Two-photon temporal compression

Efficient method for two-photon compression

Less chirp & less bandwidth to achieve the same temporal width

Dispersion control Dispersion control

• S. E. Harris, PRL 98, 063602 (2007).

Previous scheme

Dispersion control Dispersion control

Our scheme

• A. Tanaka et al, Opt. Exp. 20, 25228 (2012)

Chirped- QPM Chirped- QPM Frequency domain 200THz 375THz Time domain 4.4fs 4.4fs

Chirped-MgSLT crystals

8.000 µm 8.128 µm 8.000 µm 8.256 µm 8.000 µm 8.550 µm 8.000 µm 8.825 µm Fabricated chirped-QPM gratings no chirp Calc.

Fabrication: chirped-MgSLT crystals of different chirp rates

(1.0 mol %) Mg-doped Stoichiometric Lithium Tantalate (MgSLT)

• A. Tanaka et al, Opt. Exp. 20, 25228 (2012) (10%-chirped crystal only)

Fabricated by H.H. Lim& S. Kurimura (NIMS)

Pump photons Pertier unit 0.5mm 0.5mm 20mm Dimension Picture

• Type-0 (e+e→e) PDC process
• Flat parametric gain due to linear chirp

Maximal bandwidth of 200THz with 10%(8.0-8.8µm) chirped device

Previous SPDC experiments

Wavelength ranges of two photons agreed with theory

*After calibration of detector Q.E. Problems

• Complex measurements due to limited detector wavelength range
• Broadband single photon detectors are needed for QOCT application

Meas. Meas. Meas. Meas. Si-CCD Si-CCD InGaAs-PDA InGaAs-PDA Calc. Calc. Meas. Meas. Calc. Calc. Meas. Meas.

chirp small chirp large chirp large chirp small

5×10-6 1×10-8 1×10-7 1×10-6 5×10-8 5×10-7 5×10-6 1×10-8 1×10-7 1×10-6 5×10-8 5×10-7

New SPDC experiment

SNSPD PMT

+RF Amps.

8 µm 8.825 µm Setup

Single-photon spectra are measured both by SNSPD and PMT

Photo-Multiplier Tube

InP/InGaAs photocathode Broadband detection (<0.4-1.6 µm) Flat Q.E. for 500-1600nm New device from Hamamatsu Photonics

• M. Niigaki, T. Hirohata et al, APL 71, 2493 (1997).

Superconducting Nanowire Single Photon Detector NbN nanowire (bias current: 37 µA) Broadband detection (<0.6-2.0 µm) Q.E. exponential decays for λ Collaboration with Nanjing Univ.

• S. Subashchandran et al, Proc. SPIE 8268, 82681V-2 (2011).

Cryo-cooler (3.7K)

• A. Tanaka et al, Opt. Exp. 20, 25228 (2012)

±0.25deg. 532nm, 2W

New SPDC experiment: results

Non-collinear photons span 194THz (1.2cycle)

SNSPD PMT Calc. Calc. *Calibrated (a) detector Q.E. and (b) filter transmittances 8 µm 8.825 µm

• A. Tanaka et al, Opt. Exp. 20, 25228 (2012)

194THz 185THz (due to Q.E. of PMT) Signal Idler Signal Idler

Two-photon temporal widths

Calculated temporal correlation with different chirps

11.8 fs 10.0 fs 7.1 fs 4.4 fs 3.3 cycle 2.8 cycle 2.0 cycle 1.2 cycle

• A. Tanaka et al, Opt. Exp. 20, 25228 (2012) (max-chirped crystal only)

chirp small large

Our chirped-MgSLT can herald 1.2-cycle two-photons

Next step: measuring frequency correlation

Experimentally tested to verify broadband frequency correlation

Preliminary frequency correlation measurement ν1 ν2 APD APD ν2 ν1 PMT PMT coinci coinci dence Coincidence counts Chirped

• MgSLT

Previous measurement Chirped

• MgSLT
• Single photon spectra

are measured Chirped

• MgSLT

correlated? Question

• For QOCT application

detection of correlated modes is necessary

Preliminary results of frequency correlation

Single-photon spectrum Joint spectrum 940-1200 nm Bandwidth: 65 THz Coincidence degradation 1) Q.E. of detectors 2) Low throughput at large filter tilt

Observed two-photon frequency correlation (65THz)

65THz 8 µm 8.128 µm With 1.6% chirped device

1. Non-collinear SPDC enables an efficient two-photon compression 2. Measured collinear two-photons from four chirped-MgSLT crystals agreed with theoretical spectral width 3. Octave-spanning (820nm, 200THz) non-collinear two-photons are

• bserved using Superconducting Nanowire SPD and PMT

4. Fabricated 10%-chirped device can herald 1.2 cycle correlation 5. Two-photons emitted from 1.6%-chirped QPM grating have frequency correlation width larger than 65 THz

Acknowledgement We thank Prof. Mikio Yamashita for kind discussion and Mr. Takahiro Shimizu for instruction in device

• fabrication. This work is supported by JST-CREST, Quantum Cybernetics, JSPS-FIRST, the Japanese

Society for the Promotion of Science, the Research Foundation for Opto-Science and Technology, Special Coordination Funds for Promoting Science and Technology, a Grant-in-Aid for JSPS Fellows (11J00744), JSPS Research Fellowships for Young Scientists and the G-COE program.