Are those Lockheed-Martin guys using some kind of inteferometric method in their "patent."? So far I cannot tell from the patent but have not read very far. It's obvious they confounded wave vector with wave length. They say wavelength of entangled multiphoton scales as N which would be no good at all for increasing resolution. The wavelength of the entangled multiphoton is the same as the initial pump photon that splits into N components in parametric down conversion (as far as I know N = 2 only? But larger N conceivable.) So the write up is are garbled at the beginning causing me to lose interest in reading beyond that colossal screw up. What Creon is talking about below is independent of the L-M Skunkworks patent.

On Mar 10, 2007, at 2:33 PM, Creon Levit (NASA) wrote:

Jack:

Those references are interesting. I suggest taking a look at http://arxiv.org/abs/quant-ph/0202133

Two key sentences:

"For optical interferometers operating at several milliwatts, the quantum sensitivity improvement corresponds to an enhanced signal to noise ratio of eight orders of magnitude."

"In classical optical lithography the minimum feature size is determined by the Rayleigh diffraction limit of λ/4,where λ is the wavelength of the light.... Using the same entangled-photons technique, it is possible to image the features substantially smaller... yielding a resolution of λ/(4N)"

Note that N above is the number of photons!

I had missed this. Eight orders of magnitude improvement in atom/laser gyros! That could detect frame dragging easily & maybe torsion. Similar improvements in optical microscopy and lithography cold make a practical nanoelectronics industry, and perhaps other nanotechnology as well. How about LISA with entangled/squeezed states? It could boost the sensitivity dramatically and perhaps detect local fluctuations in dark matter & dark energy content of the vacuum? There could be similar improvements for atomic clocks, rangefinders (GPS), prospecting, low power communication (deep space?), eavesdropping, tomography, spectroscopy, holography... on and on.....

>6 order-of-magnitude improvements come along once per technological revolution. The only examples I can think of are: 1) nuclear energy vs. chemical energy, 2) electronic information processing (computation & communication) vs. mechanical information processing, and perhaps 3) molecular biology & biotechnology vs. pre-molecular biology.

This sounds too good to be true, but these are smart guys. Can you please have a look and tell me what you think of http://arxiv.org/abs/quant-ph/0202133 ?


Jack Sarfatti wrote:
Thanks, but I got stuck on their 0009 p.3 where they seem to confound wave vector with wavelength. :-)
On Mar 10, 2007, at 12:31 PM, Srikanth R wrote:

Dear Prof. Jack,

I haven't read the patent application fully, but if the applicants have got the physics right, they are probably talking about ideas in quantum metrology/quantum lithography, where path-entangled photons of the type
|0,N> + |N,0>
are used for imaging, which allows one to go beyond the Rayleigh-limited single-photon diffraction pattern, to have resolution improved N-fold.

Do you mean "vacuum" by "0" in above notation? Thanks for references. They look interesting even if the patent is not even wrong. :-)

Two references that might be of relevance:
[1] "Quantum-enhanced measurements: beating the standard quantum limit"
Giovannetti, Vittorio; Lloyd, Seth; Maccone, Lorenzo
Science 306 1330 (2004); quant-ph/0412078

[2] "A Quantum Rosetta Stone for Interferometry"
Lee, Hwang; Kok, Pieter; Dowling, Jonathan P.
Journal of Modern Optics 49 2325 (2002); quant-ph/0202133.

With best regards,
Srik.


On Mar 11, 2007, at 9:19 AM, Jack Sarfatti wrote:

On Mar 11, 2007, at 7:04 AM, Srikanth R wrote:

Dear Prof. Jack,

On Sat, 10 Mar 2007, Jack Sarfatti wrote:

Thanks, but I got stuck on their 0009 p.3 where they seem to confound wave vector with wavelength. :-)

Indeed!

On Mar 10, 2007, at 12:31 PM, Srikanth R wrote:

I haven't read the patent application fully, but if the applicants have got the physics right, they are probably talking about ideas in quantum metrology/quantum lithography, where path-entangled photons of the type
|0,N> + |N,0>
are used for imaging, which allows one to go beyond the Rayleigh-limited single-photon diffraction pattern, to have resolution improved N-fold.

Do you mean "vacuum" by "0" in above notation? Thanks for references. They look interesting even if the patent is not even wrong. :-)

Actually, path entangled states of the following type are meant:
|00000..> + |11111..>
where {|0>,|1>} are a basis for single photons. (The earlier notation is due to ref. [2]!)

With best regards,
Srik.

So that's a coherent state superposing the vacuum |0>i for the i-th mode with the single particle state |1>i with i = 1 to N modes entangled.

Barring superselection rules (the one on charge violated in superconductor) it should also work for fermions because it does not violate the exclusion principle.


On Fri, 9 Mar 2007, Jack Sarfatti wrote:

If anyone has any details on what the key idea here is mathematically I am interested. Thanks.

They obviously have a collinear pulse of entangled photon pairs from parametric down conversion

http://www.ien.it/~castelle/fig1.jpg

The entangled double pulse is reflected back.

Entangled beams allow the absorption spectrum and the resolution limit of quantum radar systems to be selected independently of one another. Thus, while classical radar systems must compromise between range and resolution, quantum radar systems can simultaneously achieve the low attenuation/high range associated with a long wave length and the high resolution associated with a short wave length.

So obviously they do two incompatible measurements of "range" and "resolution" one on each component of the entangled double beam, but, off-hand, I do not as yet see the advantage of entanglement here? "Range" is simply timing of the return pulse relative to the sent pulse. So you want the pulse width as short as possible. Short wave is a momentum measurement. The higher the momentum the shorter the wavelength. So?

Jack Sarfatti
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