Quantum Entanglement and High Brightness Laser Source (OCR)

Our focus is on demonstrating high precision (sub-micron) laser ranging for Navigation using a unique high-sensitivity optical correlation receiver with both classical laser pulses and an entangled-photon laser transmitter. We used short-pulsed diode lasers with classical short pulses to demonstarte the receiver prototype.  We published this result at a recent conference: https://spie.org/Publications/Proceedings/Paper/10.1117/12.2225947?origin_id=x4325&start_volume_number=9800   and as a NASA Tech Brief:   http://www.techbriefs.com/component/content/article/ntb/tech-briefs/photonics-optics/24127   Our next steps are 1) to use femtosecond lasers for the classical light pulses.  2) to build an entangled photon sources laser transmitter 3) to test the laser ranging precision and trades with these two sources to achieve sub-micron ranging over large distances.

1.             Abstract 

This is a new effort for the development of quantum technology and toward a world-class quantum entanglement demonstration.  We propose to develop a high brightness entangled photon source at 1064 nm using a nonlinear crystal.  The entangled photon laser transmitter and ultra-sensitive receiver permits high-precision over very large distance for orders of magnitude improvements to the Global Positioning System,  formation flying, gravity wave and field measurements and very long baseline interferometry. 

2.            Objectives

Quantum communications has recently matured from a purely fundamental research area of quantum physics to an applied science with a potentially huge economic impact.  The emergence of applications and technologies based on the foundations of quantum physics has revolutionized our understanding of information theory.  Quantum superposition and entanglement constitute a novel type of resources that enables new developments in the fields of communications, computation, and metrology.  All these quantum technology applications are based on the development of an efficient laser source for entangled pairs of photons.  This is a first and necessary step.  The overall technical objective is to demonstrate a practical use for quantum entanglement-based systems.  With an entangled photon source can pursue the following ideas: 1) quantum communication 2) precision laser ranging 3) space optical links for a world-wide network of ultra-precise clocks 4) quantum key distribution 5) improved imaging.  Our focus for this IRAD is on demonstrating high precision (sub-micron) laser ranging for Navigation using an entangled-photon transmitter and a unique optical correlation receiver.

3.            Justification

NASA Practical

The entangled photon laser transmitter and ultra-sensitive receiver permits high-precision (approaching fundamental limits) over very large distance for orders of magnitude improvements to the Global Positioning System,  formation flying, gravity wave and field measurements and very long baseline interferometry.   Our recent work on a correlation receiver provides a strong contribution to this field.  NASA Space Technology Research Fellowship (NSTRF) quantum optics PhD graduate student Timothy Rambo (Northwestern University)  (https://www.nasa.gov/directorates/spacetech/strg/2012_class.html#.V6H402VgFhM) conducted this work at NASA-GSFC with Dr. Krainak in the summer of 2015.  We used short-pulsed diode lasers to work on the prototype.  Further work is needed with femtosecond lasers (already in-hand) and entangled photon sources (proposed here).  Our work (and need) for precision ranging differentiates us from and provides a complement to the US Department of Defense (DoD) efforts.

NASA relation to US  University and DoD efforts

Our plan is to cooperate with the US University and DoD efforts.  Dr. Krainak (NASA-GSFC 554) has maintained close and continuous contact with University of Maryland Joint Quantum Institute members: Dr. Alan Midgall (http://jqi.umd.edu/people/fellows), Dr. Joshua Bienfang & Dr. Alessandro Restelli (http://jqi.umd.edu/people/research-scientists).   Ardeshir Azarbarzin (560) under direction from Chris Scolese (NASA-GSFC 100) is establishing a connection to the Space and Naval Warfare Command http://www.public.navy.mil/spawar/Pages/default.aspx

NASA relation to International efforts

Dr. Krainak has been in continuous contact with the Austrian quantum optics group that hopes to conduct a quantum entanglement experiment on the International Space Station. (http://www.iqoqi-vienna.at/home/research-groups/ursin-group/quantumopticsinspace/)

Dr. Krainak traveled to their recent meeting at the European Space Technology Center to discuss possibly collaboration in supplying a NASA laser satellite-tracking ground station.  We have been conducting optical communications laser ground station experiments at the NASA-GSFC Geoscience and Geophysical Astronomical Observatory (GGAO) and at White Sands Complex.

International competition

China recently launched a satellite to conduct quantum communication experiments  http://usa.chinadaily.com.cn/china/2016-05/23/content_25421841.htm

4.             Research and Development Plan

A. Entangled photon laser transmitter:

We propose to use a commercial of the shelf 532nm frequency doubling PPLN crystal (Thorlabs, Model SHG3-1 and SHG3-10) for parametric frequency down conversion.  The crystal will produce pairs of photons at 1064 nm when it is pumped by 532 nm laser.  We then use a polarization beam splitter to combine two orthogonal polarized beams.  Due to the uncertainty principal, the combined beam will be polarization entangled.  Figure 1 shows the proposed experiment setup.  We will perform polarization correlation test to demonstrate a violation of a Bell inequality using this entangled source.

Figure 1. Entangled photon transmitter

Coincidence detection rate will be recorded for various setting of polarizer angles.  In this case, we will only detect 50% of the entangled pairs because paired photon could both transmit through the beam splitter to APD A or to APD B.  The  Bell’s inequality test is the quantum optics standard for verifying photon entanglement and quantifying entanglement quality.  The density matrix of its state will also be analyzed using quantum state tomography (QST).

Figure 2. Simple entangled photon test system

B. Practical, High Signal-to-Noise Ratio Entangled photon receiver

Nanometer ranging with an intensity interferometer (eliminates sensitivity to vibration and need for expensive optics) with a single photon sensitive receiver can be achieved[1]. This work recently received an SPIE Best Paper Award.  We previously demonstrated a proof-of-concept optical correlation receiver that has been shown[2] to provide excellent results for entangled photons.   We constructed a fourth-order interferometer using beam splitters and quarter-wave plates as shown in Figure 3.  Both beamsplitters are polarizing. The pulsed light source was a Picoquant 780 nm wavelength laser diode with a 70 ps pulse width and 2.5 nm spectral width (360 fs coherence time).  The detectors are silicon avalanche photodiode arrays (Sensl Model MicroFC-SMA-10010) with an on-chip high-pass filtered output that provides good photon number resolution.  A random phase is introduced in one beam (e.g. with a moving mirror driven by a piezo-electric-transducer (PZT). We used an oscilloscope to subtract the outputs of the two detector arrays (directly measuring I ₁ (t) – I ₂ (t)). We measured the variance of the difference of detector outputs over 10,000 optical pulses at each micrometer position to ensure the average phase induced by the PZT was 0.  The experimentally observed fourth-order correlation peak and the theory are shown in Figure 4.  In this IRAD we will use this optical correlation receiver to integrate entangled-photons to provide sub-micron laser ranging over long distance.

 Figure 3. Fourth-order correlator proof-of-concept experiment.  Both beamsplitters are polarizing.

Figure 4.  Normalized fourth-order correlator experimental and theoretical result

C. Laser ranging experimental tests

We will conduct open-path atmospheric laser ranging experiments at the 1064 nm wavelength using the entangled-photon transceiver and our optical test range (Figure 5).

Figure 5. Cell phone tower as viewed from NASA –GSFC Building 33 fourth floor window with microprism retroreflector cooperative target (low-power laser pointer illuminated) for open-path test range.

5.    Future Development and Funding Plan

Communication and Navigation

Precision laser ranging for the Global Positioning System, formation flying and for a world-wide/planetary network of ultra-precise clocks is directly in the NASA HQ Space Comm and Nav roadmap.   A successful real-world practical demonstration of precision ranging with quantum entanglement technologies would pave the way to a NASA HQ funded effort (SCaN).

Astrophysics, Earth and planetary science

Precision laser ranging is vital to gravitational wave and gravity field measurements and very long baseline interferometry.    The understanding and analysis of the propagation of the wave function over long distances has been (since Einstein’s 1935 paper) and continues to be a fundamental physics question.  A successful real-world practical demonstration of precision ranging with quantum entanglement technologies would pave the way to a NASA HQ funded effort (APRA, ESTO-ACT, PICASSO).

[1] Femtosecond photon-counting receiver Michael A. Krainak ; Timothy M. Rambo ; Guangning Yang ; Wei Lu ; Kenji Numata Proc. SPIE 9858, Advanced Photon Counting Techniques X, 98580S (May 5, 2016);

[2] Iskhakov, T. Sh; Spasibko, K. Yu; Chekhova, M. V.; et al. "Macroscopic Hong-Ou-Mandel interference," New Journal of Physics Vol. 15, 093036 (2013)