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When people talk about the next-generation of computers, they're usually referring to one of two things: quantum computers – devices that will have exponentially greater processing power thanks to the addition of quantum superposition to the binary code – and optical computers, which will beam data at the speed of light without generating all the heat and wasted energy of traditional electronic computers.

Both of those have the power to revolutionise computing as we know it, and now scientists at the University of Technology, Sydney have discovered a material that has the potential to combine both of those abilities in one ridiculously powerful computer of the future. Just hold on for a second while we freak out over here.

The material is layered hexagonal boron nitride, which is a bit of a mouthful, but all you really need to know about it is that it's only one atom thick – just like graphene – and it has the ability to emit a single pulse of quantum light on demand at room temperature, making it ideal to help build a quantum optical computer chip.

Until now, room-temperature quantum emitters had only worked in a chunky, 3D material such as diamonds, which were never going to be easy to integrate onto computer chips. 

"This material – layered hexagonal boron nitride (boron and nitrogen atoms that are arranged in a honeycomb structure) – is rather unique," said one of the researchers, Mike Ford. "It is atomically thin and is traditionally used as a lubricant; however upon careful processing we discovered that it can emit quantised pulses of light – single photons that can carry information.

"That’s important because one of the big goals is to make optical computer chips that can operate based on light rather than electrons, therefore operating much faster with less heat generation," he added.

So how does a pulse of light work with quantum computing? In a traditional computer system, photons – particles of light – can be used to store information by being in either vertical or horizontal polarisation.

But they can also be turned into quantum bits (or qubits) by being put into superposition – a unique quantum state where they're in both vertical and horizontal polarisation at the same time. That's a big deal for security, and also processing power.

"You can create very secure communication systems using single photons,"explained team member Igor Aharonovich. "Each photon can be employed as a qubit (quantum bit, similarly to standard electronic bits), but because one cannot eavesdrop on single photons, the information is secure."

Best of all, the material just happens to also be cheap and easy to make, which means that it could be easily scaled up.

"This material is very easy to fabricate," said PhD student Trong Toan Tran. "It’s a much more viable option because it can be used at room temperature; it’s cheap, sustainable and is available in large quantities."

"Ultimately we want to build a 'plug and play' device that can generate single photons on demand, which will be used as a first prototype source for scalable quantum technologies that will pave the way to quantum computing with hexagonal boron nitride," he added.

The research has been published in Nature Nanotechnology. Now all we really want to know is whether the new material would also work with Li-Fi. If that's the case, our future is pretty much set.

UTS Science is a sponsor of ScienceAlert. Find out more about their research.

This article was written by Geoff Smith from the University of Bath. It was originally published by The Conversation.

This week, 14-year-old Lucas Etter set a new world record for solving the classic Rubik’s cube in Clarksville, Maryland, in the US, solving the scrambled cube in an astonishing 4.904 seconds. The maximum number of face turns needed to solve the classic Rubik’s cube - one that is segmented into squares laid out 3x3 on each face - is 20, and the maximum number of quarter turns is 26.

It took 30 years to discover these numbers, which were finally proved by Tomas Rokicki and Morley Davidson using a mixture of mathematics and computer calculation. The puzzle does have 43,252,003,274,489,856,000 (43 times 1018, or 43 quintillion) possible configurations after all.

So how do the likes of Lucas Etter work out how to solve Rubik’s cube so quickly? They could read instructions, but that rather spoils the fun. If you want to work out how to do it yourself, you need to develop cube-solving tools. In this sense, a tool is a short sequence of turns which results in only a few of the individual squares on the cube’s faces changing position. When you have discovered and memorised enough tools, you can execute them one after the other in order as required to return the cube to its pristine, solved condition.

These tools require experimentation to discover. Here’s how I did it myself: go on holiday with a Rubik’s cube and a screwdriver. Do experiments to find tools. The trouble is that most experiments just scramble the cube horribly and you forget what you did so you cannot undo your moves.

Now you have a choice, either buy another Rubik’s cube, or take out your trusty screwdriver. Turn one face through 45 degrees, and place the screwdriver under a central piece of the rotated face. Using the screwdriver as a lever to gently prise it out, it’s then easy to take the cube apart completely and reassemble it in pristine form.

The final move of reassembly will be the reverse of the screwdriver trick: rotate one face 45 degrees and apply gentle pressure to put the final piece back in place.

Sequences of moves of a cube form something that mathematicians call a group. If A is a sequence of moves, then let A-1 (that’s “A inverse”) be the same sequence of moves performed in reverse. So if you perform A and then A-1, the cube will be in the same state as was it when you began. The same is true if you first perform A-1 followed by A.

Now suppose that B is another sequence of moves. Many tools have the form of what mathematicians call a commutator: do A, then B, then A-1 and finally B-1. If Aand B commute, so that performing A then B is the same as doing B then A, then the commutator does nothing. From a mathematical point of view, a commutator measures failure to commute, and is a key notion in group theory. When I had a Rubik’s cube in one hand, and a screwdriver in the other, it was natural to look at how commutators behave.

Think of the overall structure of the different configurations of a Rubik’s cube as a labyrinth, which has that many chambers, each of which contains a Rubik’s cube in the state which corresponds to that chamber. From each chamber there are 12 doors leading to other chambers, each door corresponding to a quarter turn of one of the six faces of a cube. The type of turn needed to pass through each door is written above it, so you know which door is which. Your job is to navigate your way from a particular chamber to the one where the cube on the table is in perfect condition.

The tools that you have discovered are ways of getting nearer to the goal. So you don’t need to plan your route in advance, you just execute the rotations of each tool so that you get steadily closer to and finally reach the winning chamber. The mathematical result in Rokicki and Davidson’s paper shows that, no matter where you are in the labyrinth, it’s possible to reach the winning chamber by passing through at most 26 doors - although the route you find using your tools is not likely to be that efficient.

How to put this to use to solve the cube in 5 seconds? Someone like young Lucas Etta who is interested in speed solutions will not only have memorised a large number of tools, they’ll also have practised them until they can perform it very quickly. This is mostly a matter of dexterity and practice, but it’s also important to have a high-quality cube that can be manipulated smoothly and with great precision.

Others, rather than going for speed, develop the skill of solving Rubik’s cube while blindfolded or with the cube held behind their back. In the competitive version of this variation, the solver is given a limited amount of time to study the scrambled cube and plan their solution, before they have to carry out their solution from memory without looking at the cube again.

In terms of our metaphor of a labyrinth, this corresponds to all the Rubik’s cubes in all the chambers being removed, except for the one on which you start. You can’t take that cube with you, but you can study it carefully and plan your whole route to the winning chamber in advance. Quite a feat of memory, and not for those with just a passing interest in the cube.

Geoff Smith, Senior Lecturer in Mathematics, University of Bath.

This article was originally published by The Conversation. Read the original article.