A connection between quantum correlations and spacetime geometry

A connection between quantum correlations and spacetime geometry
Two fictitious observers named Alice and Bob bring space-time and quantum physics together. Credit: Quantum Information/Harald Ritsch/ÖAW

Researchers of the Academy explore the consequences of locality for measurements distributed in spacetime. Their article has now been published in the Nature journal Quantum Information.

Locality is a fundamental principle behind all physical interactions. It says that each physical system can only interact with other systems in its immediate vicinity, so that interactions between two distant objects must be mediated by an intermediary. For instance, in the familiar case of radio communication devices and mobile phones, that send and receive information over a distance, the role of the intermediary is played by electromagnetic waves. Particle physics tells us that elementary particles behave similarly. When two of them exert a force on each other, this does not happen instantaneously over distance, rather by an exchange of a particle which mediates that force locally. An important consequence of the locality of interactions is that many , such as solids as well as fields describing , satisfy the so-called "area law" property.

Alice and Bob

To explain what this property means, imagine two observers Alice and Bob, that perform measurements on the constituent parts of a whole physical system. Alice can only measure the parts that lie inside a region of space which is separated by a boundary from the rest of space; whereas Bob can perform measurements on the parts that lie outside Alice's region. The "area law" roughly means that the degree to which the outcomes of Alice's and Bob's measurements are correlated is determined by the area of the boundary that separates Alice's region from Bob's regions, rather than by the volume of the region. This is somewhat surprising, as many other thermodynamic or informational quantities, such as energy or entropy, typically scale with the volume and not the area of the region considered.

A connection between quantum correlations and spacetime geometry
The new study extends these results into the spacetime, in which Alice performs her measurements over a certain period of time. The result: Even in space-time, the law of the surface applies and the strength of the correlation depends on the area of the area in which Alice performs her measurements. Credit: IQOQI-Vienna, CC BY-NC-ND 2.0

Quantum mechanics and gravity

While area laws are typically formulated in terms of regions of space (as in our example), Einstein's theory of relativity, in which space and time are unified into one , teaches us that the proper description of physics should be in terms of interactions that are local in spacetime. This raises the question of whether the area law property can be generalised to regions in spacetime. In particular, imagine that now Alice is given access to a part of the system confined in a spatial box for a limited time in which she can perform several measurements, such that all her measurements are performed within a four-dimensional spacetime box. Bob is allowed to access the system in any point in spacetime which is outside of Alice's box. In a new publication in Quantum Information researchers of the Vienna Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences investigate whether the boundary of this four-dimensional spacetime region can tell us something about the degree of correlations between the outcomes of Alice's and Bob's measurements.

In the article, the authors show that an area law holds for spacetime regions if the physical system under consideration consists of particles interacting locally. Ĉaslav Brukner, at the academy institute and a co-author of the study, comments: "This work provides a connection between quantum correlations and spacetime geometry. These insights may prove useful for the development of future theories unifying and gravity."

Explore further

Can the causal order between events change in quantum mechanics?

More information: Ilya Kull et al. A spacetime area law bound on quantum correlations, npj Quantum Information (2019). DOI: 10.1038/s41534-019-0171-x
Citation: A connection between quantum correlations and spacetime geometry (2019, July 11) retrieved 14 October 2019 from https://phys.org/news/2019-07-quantum-spacetime-geometry.html
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Jul 11, 2019
Good to see QM examined in relation to SpaceTime. The QM forces must eventually unify with gravity; which is all about geometry of spacetime.
Entanglement implies that at the smallest scales two distant tangled particles 'spaces' are 'touching' causally. Whereas when they take time to interact via forces they are also 'not touching'!

I also look forward to the Copenhagen interpretation being replaced by something more logical:Even if its defined in some geometry of the extra dimensions of string theory.

I also look forward to a geometric solution as to why quarks, and the hadrons they 'additively' form into are constrained to exactly 1/2 spin by the space they exist in.

Jul 11, 2019
Good to see QM examined in relation to SpaceTime.


Jul 11, 2019

Jul 11, 2019
EyeNSein "I also look forward to the Copenhagen interpretation being replaced"

Numerous experiments have confirmed superposition & entanglement and so the phenomena upon which the Copenhagen interpretation is based are solid, another interpretation will not change any of the fundamentals.

String theory is a grand wishful thinking project that basically asks "what would the quantum world be like if it complied with intuitive human sensibilities and could be explained in everyday geometric terms (even if complicated)."

The first attempt at answering this question was the planetary atom model which failed and every other attempt to anthropomorphise the quantum world since including string theory has also failed.

The basic string in string theory is not based on anything physical and comes from the same philosophical edict that says that you can make up anything you like in the region beyond detection: God, multiple universes and strings, none of which is science.

Jul 12, 2019
one needs a model of the universe. Everything will come together then. Please see what spinning sphere theory has found. "Predicting the Gravitational Constant from the New Physics of a
Rotating Universe"

Jul 12, 2019
No surprises there, not since the work of Bekenstein on BH information ie Bekenstein Limit which is an area law

Jul 12, 2019
A lot of our quantum 'laws' are plucked very literally out of thin air (or spacetime!) and are dubbed as laws when they fit the experimental facts. This is OK as a starting position, but without the theorists looking to explain HOW, is intellectually empty exercise.
We are currently defending 'Copenhagen interpretation' in the same way 'earth, air and fire' was defended in ages past. Copenhagen's accuracy, and simultaneous implausibility, suggests there is something wrong with our perception and interpretation of space and time.

I'm hoping that something like Dirac's equation extended to include GR as well as it includes SR and QM will accurately explain a single 'particle' going through two slots separated, but touching, in some geometry of x dimensional spacetime.

Jul 15, 2019
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Jul 15, 2019
Mercury's precession is frame dragging, frame dragging can be simulated with hydrodynamics, anyone who could relate gravity of a spinning object to a spinning radiative flow could anticipate frame-dragging, it's like Gauss's gravity. There's is supposedly a factor of two difference between curvature of a light path and curvature in the path of an infinitesimal mass moving at a speed that is infinitesimally below light-speed, so I'm not sure how seriously to take the non-Euclidean geometry issue supposedly exhausted in light-lines and yet ignored in fundamental matter-particle lines that cannot follow light-lines.

Jul 15, 2019
"non-Euclidean geometry"

A black hole supposedly has only one radius for a photosphere, while any amount of matter could orbit around a black hole at any number of orbits, given a full range of orbital speeds is available. This diversity difference seems to sum up any conceivable Facebook-originated complaint about not being able to neatly grid out a non-Euclidean space using light-lines. Especially if it supposedly can't be summarized here. I mean if you can't have an original thought or condensation then what is the attraction to speculating.

Jul 15, 2019
The current fermionic string physics hypothesis remains the best hope for finding a theory of quantum gravity.

It's important to remember that bosonic string theory remains the primary insight into the dynamics of the colored gluons- the quanta of the color force, detailed these days in QCD, which has had many experimental successes.

It's also important to remember that a theory is not called a "law" until it has been thoroughly experimentally and observationally tested. It's not like they start calling something a "law of physics" until they've thoroughly tested it. Until then it's a theory. Both special and general relativity have been tested to this level.

Jul 15, 2019
LQG failed to make testable predictions just as badly as string physics ever did. Even after a celebrated book by Lee Smolin. Smolin now maintains that LQG and string physics are different aspects of the same underlying theory.

Jul 15, 2019
"An important consequence of the locality of interactions is that many physical systems, such as solids as well as quantum fields describing elementary particles, satisfy the so-called "area law" property."

It's not possible to not think of Gauss if someone says "area law," he had an area law for charge that became 1/4 of Maxwell's four equations, he had a similar law for gravity that few people know about. Both area laws involved the concept of force-carrier flow ("flux"). The language here reminds me more of AdS/CFT stuff more than anything, but I suppose it is basically the same thing. Einstein supposedly dispensed with the general flow and replaced it with curved space, essentially abstracting any source-motion-generated gravitational information flow into something like a vacuum membrane effect. Maybe the knock against flux gravity has been that it is not spin-2 or that carriers should follow Heisenberg's limits or that it cannot be re-normalized, but all those knocks are lame.

Jul 15, 2019
Maybe there is a mental block involving a windshield-effect analogy for gravitational-flow-spin-dragging. Instead of driving in the rain, suppose you are driving around a sprinkler. I mean if you get more rain on the front windshield maybe you should end up being gravitationally-pulled in the opposite direction as the sprinkler rotates. You have to assume the surface out-flow is always perpendicular to the surface and that the surface flow does not have a balancing corresponding energy of rotation embedded within it. Anyway, in my opinion basic gravity could be quantized in so-called "virtual" flow units of angular momentum.

Jul 15, 2019
The success of unexpectedly-thin accretion disk models for covering axis-tilt and observations of surprising low-energy thin disks maybe provide some clues suggesting the equatorial plane of a black hole could carry strongly-focused gravity, i.e. retroreflection-biased modes, a non-uniform flux type of effect seemingly not obtainable with a reasonable even-keeled 3D-filling membrane model. Maybe a membrane works decently with spin along the polar axis.

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