Tricking the uncertainty principle

May 15, 2014 by Jessica Stoller-Conrad
Tricking the uncertainty principle
The tiny aluminum device—only 40 microns long and 100 nanometers thick—in which Caltech researchers observed the quantum noise from microwaves. Credit: Chan Lei and Keith Schwab/Caltech

(Phys.org) —Caltech researchers have found a way to make measurements that go beyond the limits imposed by quantum physics.

Today, we are capable of measuring the position of an object with unprecedented accuracy, but quantum physics and the Heisenberg uncertainty principle place fundamental limits on our ability to measure. Noise that arises as a result of the quantum nature of the fields used to make those measurements imposes what is called the "." This same limit influences both the ultrasensitive measurements in nanoscale devices and the kilometer-scale at LIGO. Because of this troublesome background noise, we can never know an object's exact location, but a recent study provides a solution for rerouting some of that noise away from the measurement.

The findings were published online in the May 15 issue of Science Express.

"If you want to know where something is, you have to scatter something off of it," explains Professor of Applied Physics Keith Schwab, who led the study. "For example, if you shine light at an object, the photons that scatter off provide information about the object. But the photons don't all hit and scatter at the same time, and the random pattern of scattering creates "—that is, noise. "If you shine more light, you have increased sensitivity, but you also have more noise. Here we were looking for a way to beat the uncertainty principle—to increase sensitivity but not noise."

Schwab and his colleagues began by developing a way to actually detect the noise produced during the scattering of microwaves—electromagnetic radiation that has a wavelength longer than that of visible light. To do this, they delivered microwaves of a specific frequency to a superconducting electronic circuit, or resonator, that vibrates at 5 gigahertz—or 5 billion times per second. The electronic circuit was then coupled to a formed of two metal plates that vibrate at around 4 megahertz—or 4 million times per second. The researchers observed that the quantum noise of the microwave field, due to the impact of individual photons, made the mechanical device shake randomly with an amplitude of 10-15 meters, about the diameter of a proton.

"Our mechanical device is a tiny square of aluminum—only 40 microns long, or about the diameter of a hair. We think of quantum mechanics as a good description for the behaviors of atoms and electrons and protons and all of that, but normally you don't think of these sorts of quantum effects manifesting themselves on somewhat macroscopic objects," Schwab says. "This is a physical manifestation of the uncertainty principle, seen in single photons impacting a somewhat macroscopic thing."

Once the researchers had a reliable mechanism for detecting the forces generated by the quantum fluctuations of microwaves on a macroscopic object, they could modify their electronic resonator, mechanical device, and mathematical approach to exclude the noise of the position and motion of the vibrating metal plates from their measurement.

The experiment shows that a) the noise is present and can be picked up by a detector, and b) it can be pushed to someplace that won't affect the measurement. "It's a way of tricking the so that you can dial up the sensitivity of a detector without increasing the noise," Schwab says.

Although this experiment is mostly a fundamental exploration of the of microwaves in mechanical devices, Schwab says that this line of research could one day lead to the observation of quantum mechanical effects in much larger mechanical structures. And that, he notes, could allow the demonstration of strange quantum mechanical properties like superposition and entanglement in large objects—for example, allowing a macroscopic object to exist in two places at once.

"Subatomic particles act in quantum ways—they have a wave-like nature—and so can atoms, and so can whole molecules since they're collections of atoms," Schwab says. "So the question then is: Can you make bigger and bigger objects behave in these weird wave-like ways? Why not? Right now we're just trying to figure out where the boundary of is, but you never know."

This work was published in an article titled "Mechanically Detecting and Avoiding the Quantum Fluctuations of a Microwave Field."

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User comments : 17

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Alexander Riccio
5 / 5 (3) May 16, 2014
"10-15 meters" is NOT the diameter of a proton :)
antialias_physorg
5 / 5 (6) May 16, 2014
Exponents traditionally don't survive the copy&paste approach used by physorg.
arom
1 / 5 (3) May 16, 2014
The experiment shows that a) the noise is present and can be picked up by a detector, and b) it can be pushed to someplace that won't affect the measurement. "It's a way of tricking the uncertainty principle so that you can dial up the sensitivity of a detector without increasing the noise," Schwab says.
"Subatomic particles act in quantum ways—they have a wave-like nature—and so can atoms, and so can whole molecules since they're collections of atoms," Schwab says. "So the question then is: Can you make bigger and bigger objects behave in these weird wave-like ways? Why not? Right now we're just trying to figure out where the boundary of quantum physics is, but you never know."

Maybe understand the mechanism of the weird wave-like nature of electron particle could help the research …
http://www.vacuum...17〈=en
dirk_bruere
5 / 5 (2) May 16, 2014
0.8418 fm - close enough
Ojorf
3 / 5 (2) May 16, 2014
But it's so close!

10^-15m
swordsman
not rated yet May 16, 2014
The electric field around charges obeys Coulomb's law. In order for the electron or proton to have an edge, we will have to change Coulomb's law. In the near field, the force becomes more than proportionately large. Where is the edge for measurement? Or are we still living in the abstract world of Bohr? This is one of the main problems with Quantum Physics that some of us have problems in accepting.

What is the size of a gas? It has mass-like properties.
Whydening Gyre
5 / 5 (1) May 16, 2014
What is the size of a gas? It has mass-like properties.

Guess that depends on how closely you look.... IT IS mass - just loosely dispersed.
Whydening Gyre
3 / 5 (2) May 16, 2014
... understand the mechanism of the weird wave-like nature of electron particle could help the research …

A single electron particle has no wave-like properties. Takes at least 2 to exhibit that. 3 is better and 5 is even better.
Z99
not rated yet May 16, 2014
And I thought I could write down a wave equation for a single electron. Does the Nobel Committee take back prizes? They're going to be busy eating crow.
jalmy
2 / 5 (4) May 16, 2014
I hate to say I told you so, but I have stated many times that the uncertainty principle would be proven wrong. Uncertainty is a myth generated by the unimaginative. Trying to hold to aspects of quantum theory that are not only dumb, completely un-intuitive and increasing proven WRONG. I think it will be possible eventually to measure close enough to simulate or predict with 100% accuracy all of the information contained in something. Enabling devices such as FTL communication and star-trek style matter teleportation.
thefurlong
5 / 5 (1) May 16, 2014
... understand the mechanism of the weird wave-like nature of electron particle could help the research …

A single electron particle has no wave-like properties. Takes at least 2 to exhibit that. 3 is better and 5 is even better.

No, a single electron does have wavelike properties. If there is a potential, the electron's probability distribution will still obey the laws of QM. The potential doesn't have to be electromagnetic. For example, it could be gravitational.
Whydening Gyre
not rated yet May 16, 2014
... understand the mechanism of the weird wave-like nature of electron particle could help the research …

A single electron particle has no wave-like properties. Takes at least 2 to exhibit that. 3 is better and 5 is even better.

No, a single electron does have wavelike properties. If there is a potential, the electron's probability distribution will still obey the laws of QM. The potential doesn't have to be electromagnetic. For example, it could be gravitational.

Hey Furlong. LTNS.
Wouldn't gravitational potential pull (or push, whichever side of that coin you are on) that electron in a more predictable directional pattern? More straight, I guess I mean....
Or do you mean it is not a distinct particle, but more like a blob of something?
thefurlong
5 / 5 (1) May 16, 2014
Wouldn't gravitational potential pull (or push, whichever side of that coin you are on) that electron in a more predictable directional pattern? More straight, I guess I mean....
Or do you mean it is not a distinct particle, but more like a blob of something?


Hi WideningGyre.
A gravitational field has a potential, which means that if we tried to measure the position of an electron in a gravitational field, it would have to still follow the laws of QM in regards to that potential. That's all I meant. I may have misunderstood the point you were trying to make.
Whydening Gyre
not rated yet May 16, 2014
Wouldn't gravitational potential pull (or push, whichever side of that coin you are on) that electron in a more predictable directional pattern? More straight, I guess I mean....
Or do you mean it is not a distinct particle, but more like a blob of something?


Hi WideningGyre.
A gravitational field has a potential, which means that if we tried to measure the position of an electron in a gravitational field, it would have to still follow the laws of QM in regards to that potential. That's all I meant. I may have misunderstood the point you were trying to make.

Regardless of Newton, Einstein, QM - it's still all moving triangulation...;)
Pejico
May 16, 2014
This comment has been removed by a moderator.
Whydening Gyre
not rated yet May 17, 2014
A single electron particle has no wave-like properties. Takes at least 2 to exhibit that.
Technically speaking, at least two electrons are required for detection of one of them by their mutual interaction. A lone electron cannot be even observed, nether detected like wave or particle - so I do perceive such an insight rather trivial.


Oh, right. I forgot. Me of little mind....
Not trivial, Pej. Just lost in the noise of observational complexity...
Just out of curiousity - WHY can't a single electron be detected? IT has charge. Shouldn't matter if another electron is around or not, should it?
antialias_physorg
5 / 5 (2) May 17, 2014
A single electron particle has no wave-like properties. Takes at least 2 to exhibit that.

there's a difference between having a wavelike property and measuring that.
A single electron has wavelike properties. Always. (Scattering at a single slit is enough to show wavelike properties).
That you need an interaction with something else (e.g. a photon) to make this visible to you doesn't mean the electron doesn't have wavelike properties until you measure it

Otherwise you could do a single/double slit expriment and only measure after everything was long complete and you WOULDN'T get an interference pattern. But that is not what is observed.
RhoidSlayer
not rated yet May 17, 2014
if you want to know where something is , move it
the more times you can means you know where it is
George_Rajna
May 19, 2014
This comment has been removed by a moderator.