energy-time uncertainty principle

Jan 23, 2015 8 Replies
J

Hi,



from the page:



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" "Our analysis reveals that a minimal finite length of time must elapse in order to achieve a given success rate for distinguishing an initial quantum state from its time-evolved image using an optimal measurement," Whaley said.



The new analysis could help determine the times required for quantum tunneling, such as the tunneling of electrons through the band-gap of a semiconductor or the tunneling of atoms in biological proteins.



It also could be useful in a new field called "weak measurement," which involves tracking small changes in a quantum system, such as entangled qubits in a quantum computer, as the system evolves. No one measurement sees a state that is purely distinct from the previous state. "



Was the time required for quantum tunneling and related phenomenon not able to be calculated before, or was it just being calculated without taking energy-time uncertainty into account?



cheers, Jamie


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G

Re: tunneling time and energy, you might want to look up Alpha decay and the theory by Gamow.

George H.

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J

phys.org is a dumping ground for most anything they can get their hands on.

John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
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J

Isn't that just a rehashing/rephrasing of Heisenberg's Uncertainty Principle? ...Jim Thompson

| James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
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J

Hi,

Elon Musk subscribed to it's twitter feed!

cheers, Jamie

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R

They talk of the graininess of space,what about the graininess of time? On another track, what is the EXACT bit about the 2-slit experiment,if done one way is seen as interfering waves, and done another way is seen as scattered particles (or some such - do not remember). Would like to see both explanations. And then the hypothetical repercussion(s) of each.

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J

Hi,

I think the "energy-time uncertainty" principle from the article might also have some similarity to the Gabor limit (uncertainty in time-frequency analysis):

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"a concrete example are the resolution issues of the short-time Fourier transform?if one uses a wide window, one achieves good frequency resolution at the cost of temporal resolution, while a narrow window has the opposite trade-off."

cheers, Jamie

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E

(snip)

Hi, Jamie.

Yep, it is very much possible to calculate time for quantum tunneling e.g. in various semiconductor devices. One of the earlier practical uses was calculating times of electron tunneling in resonant tunneling diodes (double-barrier heterostructures). The easiest estimation is derived from calculating probability current of a given wave function. An example of such calculations can be found e.g. in D. R. Herrick, "Construction of bound states in the continuum for epitaxial heterostructure superlattices", Physica B+C 85, 44 (1976).

There are more advanced methods now, which, as I understand, are more helpful if you have high probability of tunneling. I could provide a few links, but have no personal experience of using those methods.

Evgeny.

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