QUBIT-Quantum Computing A History of the Future

Google claims to have built the first quantum computer that can carry out calculations beyond the ability of today’s most powerful supercomputers, a landmark moment that has been hotly anticipated by researchers.  A paper by Google’s researchers seen by the FT, that was briefly posted earlier this week on a Nasa website before being removed, claimed that their processor was able to perform a calculation in three minutes and 20 seconds that would take today’s most advanced classical computer, known as Summit, approximately 10,000 years.  The researchers said this meant the “quantum supremacy”, when quantum computers carry out calculations that had previously been impossible, had been achieved.  “This dramatic speed-up relative to all known classical algorithms provides an experimental realization of quantum supremacy on a computational task and heralds the advent of a much-anticipated computing paradigm,” the authors wrote.  

A November 2018 report by the Boston Consulting Group said they could “change the game in such fields as cryptography and chemistry (and thus material science, agriculture and pharmaceuticals) not to mention artificial intelligence and machine learning . . . logistics, manufacturing, finance and energy”.  Unlike the basic binary elements of classical computers, or bits, which represent either zeros or ones, quantum bits, or qubits, can represent both at the same time. By stringing together qubits, the number of states they could represent rises exponentially, making it possible to compute millions of possibilities instantly. 

Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers. In classical computing, a bit is a single piece of information that can exist in two states – 1 or 0. Quantum computing uses quantum bits, or 'qubits' instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values. 

"The difference between classical bits and qubits is that we can also prepare qubits in a quantum superposition of 0 and 1 and create nontrivial correlated states of a number of qubits, so-called 'entangled states'," says Alexey Fedorov, a physicist at the Moscow Institute of Physics and Technology.

A qubit can be thought of like an imaginary sphere. Whereas a classical bit can be in two states – at either of the two poles of the sphere – a qubit can be any point on the sphere. This means a computer using these bits can store a huge amount more information using less energy than a classical computer.

The Story of Rigetti

The coldest place in the universe is located in sunny California.

On the outskirts of Berkeley, inside an oversized warehouse, hangs a large white pipe. It’s a human-made contraption, a next-generation cryogenic refrigerator cooled to .003 Kelvin, or just north of absolute zero.

The pipe belongs to Rigetti Computing, the next contestant aiming to build useful quantum computers.

The company got going in 2013, when a physicist named Chad Rigetti decided that quantum computers were a lot closer to prime time than many suspected, and that he wanted to be the one to push the technology over the finish line.

In pursuit of his vision, Rigetti left a comfortable job as a quantum researcher at IBM, raised over $119 million in funding, and built the coldest pipe in history. Over fifty patent applications later, Rigetti now manufactures integrated quantum circuits that are directly linked to a quantum computer in the cloud.

One of the biggest and most exciting aspects about Rigetti, however, is their push towards democratization of quantum computing.

Right now, if you go to Rigetti’s website (www.rigetti.com), you can download Forest, their quantum developer’s kit. The kit provides a user-friendly interface to the quantum world.

With it, almost anyone can write a program and run it on Rigetti’s thirty-two-qubit computer. To date, over 120 million programs have already been run.

And other companies are fast following suit, as Microsoft, IBM, and Google have now rolled out quantum cloud services.

Google’s announcement has caused a major stir in the quantum computation community.

Indeed, the very notion of “quantum supremacy” is under scrutiny. “Supremacy” implies that quantum computers will replace traditional computation, rather than serve as a supplement.

By contrast, another term often used (proposed by Rigetti) is “quantum advantage.” According to the company, this concept is demonstrated when an algorithm run on a quantum computing platform “has either a faster time to solution, a better quality solution, or lower cost of classical compute compared to the best classical algorithm.”

In either case, quantum computation offers tremendous quantitative advantages over classical computers in a range of problem domains.

To give an idea of scale: if all the atoms of the universe were each capable of storing one bit of information, an eighty-qubit computer would have more information-storage capacity than all the atoms in the universe.

And already, current state-of-the-art quantum computers, including Google’s Sycamore and IBM’s Q53, have reached a count of 53 qubits.

Yet today, we have no concrete idea of what innovations might arise once quantum computing matures at scale. But what we do know is tantalizing.

Because chemistry and physics are quantum processes, computing in qubits will usher in what Oxford’s Simon Benjamin calls “a golden age of discovery in new materials, new chemicals, and new drugs.”

It will thrust aside today’s computing constraints to artificial intelligence, fundamentally transform cybersecurity, and allow us to simulate systems of unprecedented complexity.

As Chad Rigetti explains, “[The technology] change[s] the economics of research and development. Say you’re trying to create a new cancer drug. Instead of building a large-scale wet lab to explore the properties of hundreds of thousands of compounds in test tubes, you’re going to be able to do much of that exploration inside a computer.”

In other words, the gap between experimental question and any new solution—whether novel drug, optimized material, or personalized product—is about to become a whole lot smaller.

Brace yourself. The era of democratized, scalable, and cloud-accessible quantum computing has just begun.