Quantum Computing For Computer Scientists

Quantum computing is coming, so a lot of people are trying to articulate why we want it and how it works. Most of the explanations are either hardcore physics talking about spin and entanglement, or very breezy and handwaving which can be useful to get a little understanding but isn’t useful for applying the technology. Microsoft Research has a video that attempts to hit that spot in the middle — practical information for people who currently work with traditional computers. You can see the video below.

The video starts with basics you’d get from most videos talking about vector representation and operations. You have to get through about 17 minutes of that sort of thing until you get into qubits. If you glaze over on math, listen to the “index array” explanations [Andrew] gives after the math and you’ll be happier.

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Simple Quantum Computing in 150 Lines of Python

What does it take to build a quantum computer? Lots of exotic supercooled hardware. However, creating a simulator isn’t nearly as hard and can give you a lot of insight into how this kind of computing works. A simulator doesn’t even have to be complicated. Here’s one that exists in about 150 lines of Python code.

You might wonder what the value is. After all, there are plenty of well-done simulators including Quirk that we have looked at in the past. What’s charming about this simulator is that with only 150 lines of code, you can reasonably read the whole thing in a sitting and gain an understanding of how the different operations really affect the state.

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Quantum Electric Material Borrows from Japanese Basketweaving

Kagome is a pattern used to weave baskets from bamboo strips. The pattern is a symmetrical pattern of interlaced triangles that share corners. Scientists from MIT, Harvard, and Lawrence Berkeley National Laboratory have produced a kagome metal and found that it has exotic quantum properties.

Their paper, published in Nature (paywall), reports that the crystal made from layers of iron and tin atoms, causes electrons to flow in strange ways. The electrons bend into tight circular paths and flow along the edges without losing energy.

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Microsoft Quantum Simulator Goes to Linux and Mac

Everyone seems to be gearing up for the race to be the king of quantum computers. The latest salvo is Microsoft’s, they have announced that their quantum simulator will now run on macOS and Linux, with associated libraries and examples that are now fully open source. They have produced a video about the new release, which you can see below.

Microsoft also claims that their simulator is much faster than before, especially on large simulations. Of course, really large simulations suffer from memory problems, not speed problems. You can run their simulator locally or on their Azure cloud.

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Harvesting Energy from the Earth with Quantum Tunneling

More energy hits the earth in sunlight every day than humanity could use in about 16,000 years or so, but that hasn’t stopped us from trying to tap into other sources of energy too. One source that shows promise is geothermal, but these methods have been hindered by large startup costs and other engineering challenges. A new way to tap into this energy source has been found however, which relies on capturing the infrared radiation that the Earth continuously gives off rather than digging large holes and using heat exchangers.

This energy is the thermal radiation that virtually everything gives off in some form or another. The challenge in harvesting this energy is that since the energy is in the infrared range, exceptionally tiny antennas are needed which will resonate at that frequency. It isn’t just fancy antennas, either; a new type of diode had to be manufactured which uses quantum tunneling to convert the energy into DC electricity.

While the scientists involved in this new concept point out that this is just a prototype at this point, it shows promise and could be a game-changer since it would allow clean energy to be harvested whenever needed, and wouldn’t rely on the prevailing weather. While many clean-energy-promising projects often seem like pipe dreams, we can’t say it’s the most unlikely candidate for future widespread adoption we’ve ever seen.

Quantum Computing Hardware Teardown

Although quantum computing is still in its infancy, enough progress is being made for it to look a little more promising than other “revolutionary” technologies, like fusion power or flying cars. IBM, Intel, and Google all either operate or are producing double-digit qubit computers right now, and there are plans for even larger quantum computers in the future. With this amount of inertia, our quantum computing revolution seems almost certain.

There’s still a lot of work to be done, though, before all of our encryption is rendered moot by these new devices. Since nothing is easy (or intuitive) at the quantum level, progress has been considerably slower than it was during the transistor revolution of the previous century. These computers work because of two phenomena: superposition and entanglement. A quantum bit, or qubit, works because unlike a transistor it can exist in multiple states at once, rather than just “zero” or “one”. These states are difficult to determine because in general a qubit is built using a single atom. Adding to the complexity, quantum computers must utilize quantum entanglement too, whereby a pair of particles are linked. This is the only way for any hardware to “observe” the state of the computer without affecting any qubits themselves. In fact, the observations often don’t yet have the highest accuracy themselves.

There are some other challenges with the hardware as well. All quantum computers that exist today must be cooled to a temperature very close to absolute zero in order to take advantage of superconductivity. Whether this is because of a reduction in thermal noise, as is the case with universal quantum computers based on ion traps or other technology, or because it is possible to take advantage of other interesting characteristics of superconductivity like the D-Wave computers do, all of them must be cooled to a critical temperature. A further challenge is that even at these low temperatures, the qubits still interact with each other and their read/write devices in unpredictable ways that get more unpredictable as the number of qubits scales up.

So, once the physics and the refrigeration are sorted out, let’s take a look at how a few of the quantum computing technologies actually manipulate these quantum curiosities to come up with working, programmable computers. Continue reading “Quantum Computing Hardware Teardown”

Carbon Quantum Dots in Your Favorite Color

Citizen scientist extraordinaire [Thought Emporium] put out a new video about colorful quantum dots which can be seen below the break. Quantum dots are a few nanometers wide and you can tell which size they are by which color they fluoresce. Their optical and electrical properties vary proportionally with size so red will behave differently than purple but we doubt they will taste like “cherry” and  “grape.” Let’s not find out. This makes sense when you realize that a diamond will turn into black powder if you pulverize it. Carbon is funny like that.

[Thought Emporium] uses the video for two purposes. The first is to demonstrate the process he uses to make different size quantum dot in his home lab. The second purpose is to implore the scientific community, in general, to take better care when publishing scientific papers. A flimsy third reason is to show that the show must go on. Partway through, all the batteries for his light were dead so he hastily soldered a connection for his benchtop power supply.

We’ve mentioned [Thought Emporium] a few times before. Another of his carbon-based experiments involved graphene creation. How about magnetic DNA extraction? [Thought Emporium] did that too. If you can’t get enough magnets, how about implanting one?

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