Archive for the ‘Quantum Computing’ Category

This is the last of a series of four blogs about quantum computing. The first was a quick view into the weird world of quantum physics, followed by a look at was capabilities a quantum computer would have. Last time we looked at the significant implications a quantum computer will have on data security.

Here are some examples of where we are today:

  • MIT has created a five-qubit quantum computer (Science, March 2016).
  • D-WaveThe Canadian company D-Wave Systems shipped its first quantum computer in 2010 with 128 qubits. D-Wave has announced the availability of the D-Wave 2X system with more than 1,000 qubits. On the other hand, there are lots of skeptics about whether what D-Wave is creating is really a quantum computer. It clearly uses some quantum capabilities, but if I understand it correctly (a big “if”), it deliberately avoids using superposition and quantum entanglement. If so, it will limit their quantum computer capabilities. However, they are way ahead of anybody else in actually building a computer based on quantum concepts.
  • The Australian company Shoal created a quantum computer for the Australian Department of Defense in 2014, and then spun off QxBranch as a quantum computing software company working closely with D-Wave.
  • California-based Rigetti Computing is developing fault-tolerant gate-based solid state quantum processors that they claim is highly scalable and low cost.

The largest prime number successfully factored by a quantum computer is 56,153 (241 x 233). At this point, the time to factor that 16-bit number with a quantum computer is longer than the time to factor it on modern classical computer. Today’s modern encryption keys have up to 768 bits.

How long will it take to have a quantum computer large enough to threaten today’s network security practices? It took 25 years from the first digital computer (Eniac, 1946) until computers were powerful enough and ubiquitous enough to create the first primitive networks (ARPANET, 1971). It took another 19 years until Tim Berners-Lee created the first web browser in 1990 and the formation of the Internet. It won’t take that long to get real quantum computers, maybe twenty years but more likely closer to ten.

The last word:

You don’t have to worry about a quantum computer cracking your network security and exposing all of your secrets. Yet. You do need to remain vigilant because sometime there will be such a quantum computer. You can bet the first such computers will be deep inside organizations like the US National Security Agency (NSA) and similar organizations in other countries.

For those of us who lived through or even participated in the space race, one of the significant differences between the US and the USSR was openness: the US did everything in public, the USSR did everything in secret and only revealed their successes after the fact. These days, the NSA acts much more like the Soviet model, keeping a tight rein on security products, and with the ability and inclination to prevent technologies from entering the marketplace until the NSA is ready.

Our first indication of the existence of a powerful quantum computer may be the successful attack on a nation’s political, military, financial or physical infrastructure.

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This is the third in my Quantum Computing series. Last time I indicated that the two main areas in which quantum computers will be very much faster than digital computers are searching and factoring. The average individual and almost every company will rarely need the incredible searching capabilities of a large quantum computer, and I suspect that specialized companies will be created in the next twenty years or so to handle the special cases that do come up.

But everyone should be concerned about a quantum computer’s capability to almost instantaneously factor large numbers. To understand why, we have to understand how encryption is actually done in our digital world. There are two main types of encryption: symmetric-key encryption and public-key encryption.

Symmetric-key encryption uses the same key for both encryption and decryption. Both parties must have the same key in order to communicate securely. We use symmetric-key encryption every day: whenever you see https:// (instead of just http://) in an Internet URL, you are using symmetric-key encryption. Symmetric-key encryption algorithms are subject to various attacks based on the process that generates the symmetric key, but the biggest issue is how to securely transmit the key between the two parties. That key sharing usually involves some form of public-key encryption.

Public-key encryption has two keys: a published key that anyone can use to encrypt messages and a private decryption key that only the receiver has. While the process to generate the pair of keys is mathematically amusing, the key component of the process is to multiply two very large prime numbers together. The public key is that product plus another calculated value based on the two primes that form the product. The security of public-key encryption is based on the time it takes with current digital technology to determine the two prime factors that are used to compute the public and private keys. This factoring time goes up exponentially as the key gets larger, so that today by the time some organization could break a code, the data would be of historical interest only.

However, Peter Shor at MIT has shown that a quantum computer could factor large numbers easily, meaning very quickly. Oops.

Quantum computers could end the predominance of public-key encryption algorithms, which would also seriously impact symmetric-key encryption.

The ideal cryptographic protocol is the “one-time pad,” first described in 1882. A one-time pad is a random secret key that is only used once. It was original an actual pad of paper that contained the key, or more likely a set of keys. The pads were then physically carried from one party to the other, often using clandestine methods. The KGB created one-time pads that could fit inside a walnut shell. Today, most symmetric-key algorithms create a one-time use key in real time for short-term use. For example, https security creates a new key for each communication session. If you are communicating with https to multiple sites at the same time from the same browser, each of those communications has a different symmetric key.

Quantum computing to the rescue: Quantum Key Distribution (QKD) allows for the distribution of completely random keys at a distance solving the biggest security problem with symmetric-key encryption. A key generator creates two entangled qubits (perhaps a photon), and sends one to each party. Each party looks at one attribute of the qubit (say polarity), and assigns a bit (0 or 1) based on the attribute value. Due to entanglement, both parties will get the same answer. Repeating this process can generate a symmetric key of any appropriate length, normally no larger than 256 bits.

More importantly, the parties can tell if anyone intercepted their qubit. If someone does intercept the qubit distribution, that interception will disturb the entanglement and the keys will no longer match. Problem solved.

The last word:

Perhaps one of the strangest potential uses of a quantum computer is to simulate quantum systems. This will allow scientists to understand what is really happen at the quantum level, and could perhaps lead to amazing new products in a variety of areas.

We have no idea what the quantum computer will eventually do. Howard Aiken was a pioneer computer engineer and the original conceptual designer behind the IBM Harvard Mark I computer in 1944. In 1952, he said, “Originally one thought that if there were a half dozen large computers in this country, hidden away in research laboratories, this would take care of all requirements we had throughout the country.”

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Last time we talked about the weird quantum universe, where particles can be in more than one state at the same time and can be entangled with another particle at great distances. What does this have to do with computers?

Since their beginning in the late 1930s, all digital computers are based on binary digits (bits), which can have a value of zero or one. Early computers might have a few thousand bits in a box the size of a refrigerator. Your smart phone probably has more than 100 billion bits in a box that fits in your pocket. Digital computers work because the computer can tell a particular bit to be a zero or a one, and it will stay in that state until it is explicitly told to change. This is a good thing, and a bad thing. It is good because we can rely on the state of that bit. It is bad because it takes time to set the value of a bit, and later to look at it to see what that state is. Because of that, there are problems that would take computers millions of years to solve.

The quantum world is a little different. Niels Bohr who won the 1922 Nobel Prize in physics for his work in quantum theory famously said, “If quantum mechanics hasn’t profoundly shocked you, you haven’t understood it yet.”

Quantum computers use quantum bits, called qubits. Qubits are very small; they must be to have quantum effects. They can be individual atoms, photons, or electrons. Unlike a digital computer, each qubit can be in multiple states simultaneously. The effect of that is that a quantum computer with a single qubit could solve two simple problems at the same time, one with two qubits could solve four simultaneously, and one with ten qubits could solve over a thousand simple problems simultaneously. This is called parallelism. A 30-qubit quantum computer would be at least a thousand times faster than today’s conventional desktop computer.

To solve very complex problems, the digital world has created computers to take advantage of problems that can be solved using parallelism techniques. Computer companies have created computers with dozens to thousands of separate processors, each doing the same function across a large array of data. IBM’s Blue Gene is one example of a massively parallel supercomputer. SETI@home (Search for Extraterrestrial Intelligence) is an example of a distributed parallelism approach, often called grid computing, where 290,000 computers around the world can work on the same problem across the Internet.

Blue Gene cost $100 million to build. SETI takes advantage of idle time on lots of computers, so it hard to put a dollar cost on it. In ten years, it managed to cover only about 20% of the celestial sphere.

One problem with a qubit is that if you look at it, it assumes a specific state and stays there; superposition disappears. This is where entanglement comes in: you can indirectly look at the value of qubit’s attribute.

Armed with a quantum computer, what could you do? In general, not what you do today on your digital mainframe, desktop, or phone. A quantum computer would be lousy at balancing a checkbook, creating a spreadsheet, or writing a book. (Unless you were trying to prove the infinite monkey theorem: a monkey sitting at a typewriter hitting the keys at random would eventually write the complete works of William Shakespeare.)

Quantum computers will be very good in two areas: search and factoring.

  • If you have a lot of data to search (like the SETI problem), a quantum computer could look at all of the data at once.
  • While it is easy for a digital computer to multiply two large numbers, even if they each have hundreds of digits. Determining the factors of a very large number, like one with 500 digits in it, is very difficult and can take thousands of years with today’s fastest computers. A quantum computer could factor a 500-digit number in seconds.

OK, a very quick search would be neat but Google is fast enough for me. And I never even want to think about factoring a 500-digit number, so I don’t care about that.

Next time we will explore why you should care.

The last word:

As you probably know, the US is far behind most of the rest of the world in cell phone and credit card technology. Almost every point of sale in Europe takes EMV cards, smart cards that store the card data in integrated circuits embedded in the cards or in RFID chip. If you are wondering what the acronym “EMV” stands for, it is ”Europay, Mastercard and VISA,” the three companies that created the standard.

There are two security concerns you should be aware of:

  1. The RFID chips in your smart credit card can be read over a distance of up to three feet. Anyone close to you for a second could be a thief stealing your card. Always carry it in an RFID shielded envelope, wallet, or purse.
  2. Because non-smart cards are a pain for the retailers in Europe, they don’t like to take them and when they do they are not very careful. They won’t bother checking the signature on the card, even if you have signed it with “CHECK ID.” Anyone who steals your physical card will have no problem using it. Your credit card company should cover your costs, but it will be a huge pain. Never carry debit cards – you have very little protection against someone emptying your bank account, and they can do it in a matter of minutes.

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In my last post I indicated that the fifty-year trend of doubling computer processing power every two years was coming to an end, and growth with the current integrated circuit technologies is expected to become almost flat by 2018. One of the possible ways around this limit is quantum computing. Quantum computers take advantage of the strange world of quantum mechanics.

This is the first in a series of planned posts to give a brief overview of quantum physics (with no math), a discussion of quantum computers, the potential impact of them especially as it pertains to data security, and the current state of development of quantum computers.

Most of us spend nearly all of our time in a Newtonian physical environment. If we drop something, it falls, and we can predict how long it will take to fall. We can throw a baseball with, depending on our skill, a reasonable expectation that we know where it will go. We know how long it will take for something to travel between two points, subject to understandable issues like traffic jams, construction, or weather. This works whether we are trying to drive to the grocery store or land a spacecraft on Mars.

But outside of this environment, things may work differently. At really high speeds, relativity has an effect. NASA scientists were able to measure this, admittedly very small, effect on the Apollo missions to the moon: the astronauts aged a tiny fraction of a second less the rest of us stuck on earth due to the speed of their travel to and from the moon. At very small sizes, quantum effects take over, and some of these effects may seem to be just weird.

One of these weird effects is the uncertainty principle: if you measure one aspect of a quantum particle you will not be able to measure another. At the quantum level, a policeman could determine how fast you were driving, but could not then determine where you were.

Superposition is the principle that a quantum object is actually in all possible states simultaneously all the time, until something checks it. You have probably heard of the “Schrodinger’s cat” thought experiment: place a live cat in a steel box along with a sealed vial of a highly poisonous gas, a hammer, and a very small amount of radioactive material, plus a very sensitive radioactive decay sensor (e.g., Geiger counter). If the sensor detects the decay of a single radioactive atom during the test period, a relay causes the hammer to fall on the vial of gas and the cat dies. If not, the cat lives. We cannot know the state of the cat until we actually break into the box and look, and in the quantum world the cat is both dead and alive, until we observe it. If you are a cat lover, then substitute “evil squirrel” for “cat” in this paragraph. Like most thought experiments, this one is technically flawed; a cat is not a quantum entity and “looking” at one cannot change it’s living state.

Quantum entanglement may be one of the strangest concepts in the weird quantum world. If two particles are entangled, then if you measure one property of one of the particles, then the same property of the other particle is identical. Measuring the property of the one particle fixes the property for the other particle, so if it is also measured it will always be the same as the first particle. Somehow, the second particle learns the result from the first particle, and this happens instantaneously over any distance. When the particles are far enough apart, this “learning” travels faster than the speed of light. However, you do not learn anything about another property of the entangled pair. Any other property still has all of its possible values on each particle, and there is no relation of that value between the particles. For example, assume these entangled quantum particles had two properties: color (red or green) and shape (cube or sphere). Then if you measured the shape of one of the particles and found it to be a cube, then the other particle would also be a cube. However, the color of each particle could be red or green independently.

As the current computer chip technology gets faster, the individual components on the chip of necessity get smaller and closer together. At the speed our current chips operate, the speed of light is too slow. We need to have components as close to each other as possible to minimize the time it takes a signal to travel between components. At this time, components may be the size of a molecule. Chips with this level of component density face three main challenges: high defect rates, process variation, and quantum effects. The first two challenges are simply the result of the closer tolerances in the actual manufacturing phase. The industry has been pushing these limits for the past couple of decades, resulting in the continuous development of more exacting, and more expensive, manufacturing methods as well as more stringent testing processes.

Quantum effects are not as easily overcome. They can cause high leakage currents and large variability in the device’s characteristics. As transistors get smaller, quantum superposition will make it impossible to distinguish between the two states of a transistor. The real barrier to unlimited performance increases in computers using today’s technology is the reality of the quantum universe.

The last word:

The two main national political conventions / carnivals are over. The Republican convention in Cleveland had no fence around the convention center, and fewer than 25 arrests for the entire four days. The Democratic convention in Philadelphia had an eight-foot tall fence around the convention arena, raised in part to twelve feet after the first night. There were more than 50 protestors cited and removed by police during the first day alone, and those protests were literally drowned out by several severe thunderstorms with gale-force winds.

Please do not jump to any conclusions from these data points. As I have said before, apparent correlation does not imply causation. The different results may be more due to the difference between Cleveland and Philadelphia, or the weather, then the political parties.

One clear distinction that is caused by the parties is the presence, or absence, of the US flag within the convention. For the first two days of the Democratic convention, there were no US flags within the convention center, a sports arena. The Democratic committee had all of the US flags removed, including the huge one that has always hung above the center in the arena. Apparently, it interfered with the balloons.

Alas, the American voter is left with the sad choice between a clown and a criminal.

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