Friday 20 January 2012

Crack Blind Quantum Computing, We Dare You

Quantum computing will use the inherent uncertainties in quantum physics to carry out fast, complex computations.


A report in Science shows the trick can extend to "cloud" services such as Google Docs without loss of security.


This "blind quantum computing" can be carried out without a cloud computer ever knowing what the data is.


Quantum computing has been heralded as the most powerful potential successor to traditional, electronics-based computing.


One of the peculiarities of the branch of physics called quantum mechanics is that objects can be in more than one state at once, with the states of different objects tied together in ways that even Albert Einstein famously referred to as "spooky".


Instead of the 0 and 1 "bits" of digital computing, quantum computing aims to make use of these mixed and entangled states to perform calculations at comparatively breathtaking speeds.


Other quantum trickery comes in cryptography, the art of encrypting data. Data is encoded in delicately prepared states - most often those of single particles of light called photons - and the data cannot be "read" without destroying them.


While other researchers have described a blind quantum computing protocol, Barz's team appears to be the first to have actually demonstrated one working.
The researchers from Austria, Ireland, Singapore, Canada, and the U.K. write that their findings could pave the way for "unconditionally secure quantum cloud computing." The team reports that it was able to "exploit the conceptual framework of measurement-based quantum computation that enables a client to delegate a computation to a quantum server" and thus create input, computation, and output processes on the target system in such a way that it "all remain[s] unknown to the computer."
In less rarified terms, what this means is that in the future you might be able to use a cloud service like Google Docs to do some computational business on someone else's servers, secure in the knowledge that there is literally no way for the servers' owner or even the server itself to detect what you're doing.
Thank the Uncertainty Principle for that—simply by observing a quantum computational operation, you would change it. In the case of Deutsch's algorithm and Grover's algorithm, which the researchers sent to their quantum computer to perform and then send back to them, it would mean that if you somehow could get a peek at those operations, the intelligibility of what was transpiring would be destroyed before you ever got a chance to look at it.
And the process is actually blind going both ways. According to the scientists, whoever sent an algorithm to a quantum computer for it to perform wouldn't be able to see inside that system either.

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