Feeds

Spooky action at a distance is faster than light

Chinese boffins put the clock on information transfer between entangled particles

Intelligent flash storage arrays

As Einstein put it, it's impossible for anything – even information – to move faster than the speed of light. Yet the lower bound of that impossibility, the minimum speed at which entanglement can't possibly be transmitting information between two particles, appears to be around four orders of magnitude higher than c, the speed of light in a vacuum.

When describing his objections to quantum physics, one of Einstein's thought experiments was to consider the creation of a pair of entangled particles, which would retain the property of entanglement no matter how great the distance that might later separate them: the state of each entangled particle would somehow affect the other, no matter how great the distance separating them.

As far as Einsten was concerned, that was a no-no, since keeping entanglement intact demanded information transfer take place at greater than the speed of light – a violation of the general relativity.

So: since we know that entanglement exists (it's been observed and is the basis of so-called "quantum teleportation"), it's perfectly reasonable to ask at what rate the information transfer is violating general relativity?

According to this paper at Arxiv, once Earth's inertial frame of reference is taken into account, the lower bound of the speed of “spooky action” is 1.38 x 104 the speed of light in a vacuum.

The researchers say that to guarantee that what they were measuring was truly the result of entanglement – and not, for example, the outcome of coincidence – they needed to set at least one record, and observe a continuous violation of Bell's inequality for 12 hours.

Experimental setup for measuring the speed of spooky action

Source: University of Science and Technology of China

Since there needs to be enough separation between the two entangled photons as to enable a valid measurement of how long the entangled behaviour seems to pass from one particle to another, they also needed sufficient separation between the two ends of the experiment.

The researchers, from the Department of Modern Physics at the University of Science and Technology, China in Shanghai, separated their “Bob and Alice” photon detectors by 16 Km in the Qinghai Lake province: one device was placed at a scenic lookout, the other at a fish farm. Between the two is the photon source and its associated equipment.

To keep the experiment operation for 12 hours, the researchers say they created a tracking system ensuring that the signals weren't lost, and conducted the experiment at night-time so they didn't have to cope with daylight. ®

Intelligent flash storage arrays

More from The Register

next story
MARS NEEDS WOMEN, claims NASA pseudo 'naut: They eat less
'Some might find this idea offensive' boffin admits
LOHAN crash lands on CNN
Overflies Die Welt en route to lively US news vid
Comet Siding Spring revealed as flying molehill
Hiding from this space pimple isn't going to do humanity's reputation any good
Experts brand LOHAN's squeaky-clean box
Phytosanitary treatment renders Vulture 2 crate fit for export
No sail: NASA spikes Sunjammer
'Solar sail' demonstrator project binned
Carry On Cosmonaut: Willful Child is a poor taste Star Trek parody
Cringeworthy, crude and crass jokes abound in Steven Erikson’s sci-fi debut
Origins of SEXUAL INTERCOURSE fished out of SCOTTISH LAKE
Fossil find proves it first happened 385 million years ago
prev story

Whitepapers

Cloud and hybrid-cloud data protection for VMware
Learn how quick and easy it is to configure backups and perform restores for VMware environments.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.