Researchers devise a way to make a simple quantum computer using holograms

Dec 21, 2011 by Bob Yirka report
Volume holographic design of the fth of eight independent recordings used to generate the QT unitary transformation, U^QT , in PTR glass. For more information, please see the arxiv article.

(PhysOrg.com) -- Wouldn’t it be nice if we could just jump from using computers based on circuits to machines based on quantum bits (qubits)? Things would run ever so much faster. Alas, the problem is, scientists have to first figure out how to make it all work, and thus far, little real progress has been made.

One of the main problems is that in using light as the medium, there needs to be a way to have the photons interact in a measurable way, to see if the qubit is representing an on or off state. Thus far, researchers have used something called interferometers to do the job, which unfortunately because of their high sensitivity, tend to come out of alignment easily and often; not something that leads to good computing.

Things are looking up however, as new research being done at the Air Force Research Laboratory in Rome, New York by a team of computer scientists, suggests that interferometers could be embedded in a , as they describe in their paper published on the preprint server arXiv; in effect, freezing them in place and preventing them from going out of alignment.

That’s the good news. The bad news is that using holograms to freeze the interferometers in place would mean that they couldn’t reprogrammed; thus the resulting computing device would be but a one trick pony. There’s also the problem of scalability, because the use of interferometers means using the output of one as input to the next and because holograms by their nature take up a certain amount of space, it would mean stacking millions or even billions of them, which just wouldn’t be practical.

Currently the team is looking at an off the shelf product called the OptiGate to build their holographic interferometers, which would be easy and convenient, which is good because even if the final product can’t be used as a true computer, it does seem possible that they could be used as a dedicated component on a larger system for such tasks as error-correction computations or in memory busses. There’s also the optimism factor at stake here. Building a computer that used quantum components would surely breed more enthusiasm for added research into finding a way to build a truly quantum computer, the holy grail of computer technology.

Explore further: X-ray laser probes tiny quantum tornadoes in superfluid droplets

More information: Quantum computing in a piece of glass, arXiv:1112.3489v1 [quant-ph] arxiv.org/abs/1112.3489

Abstract
Quantum gates and simple quantum algorithms can be designed utilizing the diffraction phenomena of a photon within a multiplexed holographic element. The quantum eigenstates we use are the photon's linear momentum (LM) as measured by the number of waves of tilt across the aperture. Two properties of quantum computing within the circuit model make this approach attractive. First, any conditional measurement can be commuted in time with any unitary quantum gate - the timeless nature of quantum computing. Second, photon entanglement can be encoded as a superposition state of a single photon in a higher-dimensional state space afforded by LM. Our theoretical and numerical results indicate that OptiGrate's photo-thermal refractive (PTR) glass is an enabling technology. We will review our previous design of a quantum projection operator and give credence to this approach on a representative quantum gate grounded on coupled-mode theory and numerical simulations, all with parameters consistent with PTR glass. We discuss the strengths (high efficiencies, robustness to environment) and limitations (scalability, crosstalk) of this technology. While not scalable, the utility and robustness of such optical elements for broader quantum information processing applications can be substantial.

via ArXiv Blog

Related Stories

Cambridge University puts Newton's papers online

Dec 12, 2011

(PhysOrg.com) -- In a project that has long been overdue, Cambridge University, thanks to a hefty gift from the Polonsky Foundation (supporter of education and arts) and a grant from Britain’s Joint ...

Intel unveils Knights Corner - 1 teraflop chip

Nov 17, 2011

(PhysOrg.com) -- Rajeeb Hazra, Intel’s general manger of technical computing, surprised a group attending this year’s SC11 conference, at a steak house in Seattle this past week, by holding up ...

String theory researchers simulate big-bang on supercomputer

Dec 14, 2011

(PhysOrg.com) -- A trio of Japanese physicists have applied a reformulation of string theory, called IIB, whereby matrices are used to describe the properties of the physical universe, on a supercomputer, to effectively sho ...

Sony hints at holodeck future with captivating videos

Dec 05, 2011

(PhysOrg.com) -- You have to hand it to the imaginative people at Sony, or at least those they partnered with at Studio Output and the Marshmallow Laser Factory; together the three have produced three videos ...

Recommended for you

What is Nothing?

4 hours ago

Is there any place in the Universe where there's truly nothing? Consider the gaps between stars and galaxies? Or the gaps between atoms? What are the properties of nothing?

On the hunt for dark matter

7 hours ago

New University of Adelaide Future Fellow Dr Martin White is starting a research project that has the potential to redirect the experiments of thousands of physicists around the world who are trying to identify the nature ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

sender
not rated yet Dec 22, 2011
Sounds like USAF needs quantum phase locked gas lensing as a holography medium so reflectance / wave-guidance can be tunable and dynamic.
sirchick
not rated yet Jan 16, 2012
Can any thing from a Classical computer be used in a quantum computer at all to create of sorta "half way there" computer? Thats surely better than nothing but i don't know the science on this subject.