Thursday 24 December 2015

Santa Part III / High Tech Part II

The story so far? Why should I try to restrict or define what Santa can do ? He obviously does very well on his own, thank you very much!

In the interests of furthering young people's interest in science, STEM (Science, Technology, Engineering, and Mathematics) Santa has decided to share some of his secrets this Christmas Season.  or at least make some suggests that may be worth pursuing.

Last May 21st I believe this question was raised: What is really real?  

And there is more to: The Physics of Santa Claus 
- by a team of Norse investigators covering such topics as Ion-shield, Einstein = Santa Claus, Santa Claus - a threat to the environment, Santa sees you, Flying reindeer, Papa with a fake beard.  It is interesting that they suggest a connection with Albert Einstein. The following was published in NATURE on Dec 2, 2015 - I try to keep up with the suggestions!  Measuring entanglement entropy in a quantum many-body system
Before I suggest other literature here, I will try to establish the relevance of this. Consider what could be done if this were connected via drones to 3D printing in space
I, a mere mortal make this suggestion; however, if I can think of it then surely Santa who is older and much wiser than I, has at least an equal or better solution than that one. So young people if you want to join the Santa team, forget about hollywood and start studying - and do not forget to play a lot and smile for Santa is a jolly old elf.

Some of you have no doubt wondered if Santa could automate the construction of toys, as in Magnetic nanoparticles: Self-assembly at the limit
(Start small and build big - like subroutines in computer programs - don't build monolithicly.)
One of course needs control and controllers over this. In short Santa would need a computer and logic functions like Multi-element logic gates for trapped-ion qubits
If I know this then Santa too must know that  "precision control over hybrid physical systems at the quantum level is important for the realization
of many quantum-based technologies. In the field of quantum information processing (QIP) and quantum
networking, various proposals discuss the possibility of hybrid architectures1 where specific tasks
are delegated to the most suitable subsystem. For example, in quantum networks, it may be advantageous
to transfer information from a subsystem that has good memory properties to another subsystem that
is more efficient at transporting information between nodes in the network."

I do not expect you to follow up on this but I will give you some abstracts that indicate that Arthur C. Clarke's idea of technology vs magic may not be far off the mark:

Entangling two transportable neutral atoms via local spin exchange

Nature 527, 208–211 (12 November 2015) doi:10.1038/nature16073
A. M. Kaufman,    B. J. Lester,    M. Foss-Feig,    M. L. Wall,    A. M. Rey    & C. A. Regal

To advance quantum information science, physical systems are sought that meet the stringent
requirements for creating and preserving quantum entanglement. In atomic physics, robust
two-qubit entanglement is typically achieved by strong, long-range interactions in the form
of either Coulomb interactions between ions or dipolar interactions between Rydberg
atoms1, 2, 3, 4. Although such interactions allow fast quantum gates, the interacting atoms
must overcome the associated coupling to the environment and cross-talk among qubits5, 6, 7, 8.
Local interactions, such as those requiring substantial wavefunction overlap, can alleviate
these detrimental effects; however, such interactions present a new challenge: to distribute
entanglement, qubits must be transported, merged for interaction, and then isolated for storage
and subsequent operations. Here we show how, using a mobile optical tweezer, it is possible to
prepare and locally entangle two ultracold neutral atoms, and then separate them while preserving
their entanglement9, 10, 11. Ground-state neutral atom experiments have measured dynamics
consistent with spin entanglement10, 12, 13, and have detected entanglement with macroscopic
observables14, 15; we are now able to demonstrate position-resolved two-particle coherence via
application of a local gradient and parity measurements1. This new entanglement-verification
protocol could be applied to arbitrary spin-entangled states of spatially separated atoms16, 17.
The local entangling operation is achieved via spin-exchange interactions9, 10, 11, and quantum
tunnelling is used to combine and separate atoms. These techniques provide a framework for
dynamically entangling remote qubits via local operations within a large-scale quantum register.

Advances in quantum teleportation
Nature Photonics 9, 641–652 (2015) doi:10.1038/nphoton.2015.154
Received 03 June 2014 Accepted 23 July 2015 Published online 29 September 2015
S. Pirandola,    J. Eisert,    C. Weedbrook,    A. Furusawa    & S. L. Braunstein

Quantum teleportation is one of the most important protocols in quantum information. By exploiting
the physical resource of entanglement, quantum teleportation serves as a key primitive across a
variety of quantum information tasks and represents an important building block for quantum
technologies, with a pivotal role in the continuing progress of quantum communication, quantum
computing and quantum networks. Here we summarize the basic theoretical ideas behind quantum
teleportation and its variant protocols. We focus on the main experiments, together with the
technical advantages and disadvantages associated with the use of the various technologies,
from photonic qubits and optical modes to atomic ensembles, trapped atoms and solid-state systems.
After analysing the current state-of-the-art, we finish by discussing open issues, challenges and
potential future implementations.

Quantum superposition at the half-metre scale
T. Kovachy,    P. Asenbaum,    C. Overstreet,    C. A. Donnelly,    S. M. Dickerson,   
A. Sugarbaker,    J. M. Hogan    & M. A. Kasevich
Nature 528, 530–533 (24 December 2015) doi:10.1038/nature16155
Received 19 June 2015 Accepted 09 October 2015 Published online 23 December 2015
The quantum superposition principle allows massive particles to be delocalized over distant positions.
Though quantum mechanics has proved adept at describing the microscopic world, quantum superposition
runs counter to intuitive conceptions of reality and locality when extended to the macroscopic scale1,
as exemplified by the thought experiment of Schrödinger’s cat2. Matter-wave interferometers3, which
split and recombine wave packets in order to observe interference, provide a way to probe the
superposition principle on macroscopic scales4 and explore the transition to classical physics5.
In such experiments, large wave-packet separation is impeded by the need for long interaction
times and large momentum beam splitters, which cause susceptibility to dephasing and decoherence1.
Here we use light-pulse atom interferometry6, 7 to realize quantum interference with wave packets
separated by up to 54?centimetres on a timescale of 1 second. These results push quantum
superposition into a new macroscopic regime, demonstrating that quantum superposition remains
possible at the distances and timescales of everyday life. The sub-nanokelvin temperatures of
the atoms and a compensation of transverse optical forces enable a large separation while
maintaining an interference contrast of 28 per cent. In addition to testing the superposition
principle in a new regime, large quantum superposition states are vital to exploring gravity
with atom interferometers in greater detail. We anticipate that these states could be used to
increase sensitivity in tests of the equivalence principle8, 9, 10, 11, 12, measure the
gravitational Aharonov–Bohm effect13, and eventually detect gravitational waves14 and phase
shifts associated with general relativity12.

Subject terms: Quantum mechanics Ultracold gases Matter waves and particle beams

So I expect by now all good/nice children are sound asleep - maybe the parents too? Learning is hard work and requires lots of concentration, and outdoor play and exercise. Drink lots of water and sleep well.
And yes, I sleep with my beard outside the blankets! Love to all and to all a good night


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