Quantum Supremacy

What is “quantum supremacy”?

• The phrase “quantum supremacy” was coined in 2012 by John Preskill.
• Quantum supremacy refers to a quantum computer solving a problem that cannot be expected of a classical computer in a normal lifetime.
• A quantum machine is based on a branch of physics called quantum mechanics, the science that governs how matter behaves on the atomic scale.
• Google claims to have achieved a long-sought breakthrough called “quantum supremacy”, which could allow new kinds of computers to do calculations at speeds that are inconceivable with today’s technology.
• Google’s quantum computer took under 3 minutes for a calculation that would take a supercomputer 10,000 years.
• Google’s quantum computer, named Sycamore, used a 53-qubit processor to generate a sequence of millions of numbers.

Quantum Computing vs Traditional Computing

• Traditional computers work on the basis of the laws of classical physics, specifically by utilizing the flow of electricity. 
• Quantum computing relies on the way some objects act at the subatomic level or when exposed to extreme cold, like the metal chilled to nearly 460 degrees below zero.
• By harnessing this odd behavior, scientists can build a quantum bit, or “qubit”. A qubit is not always 0 or 1, but can be both at the same time (a state called quantum superposition). Only at the end of the computation would you know which, but during the computation process, its exact state is indeterminate, and Conventional computers process information in ‘bits’ or 1s and 0s, following classical physics under which our computers can process a ‘1’ or a ‘0’ at a time.
• Two qubits can hold four values at once. And as the number of qubits grows, a quantum computer becomes exponentially more powerful.
• Because of quantum superposition, a quantum computer — if it works to plan — can mimic several classical computers working in parallel.
• World’s most powerful supercomputers today can juggle 148,000 trillion operations in a second and requires about 9000 IBM CPUs connected in a particular combination to achieve this feat.
• At that tiny scale, many laws of classical physics cease to apply, and the unique laws of quantum physics come into play.
• Unlike classical physics, in which an object can exist in one place at one time, quantum physics looks at the probabilities of an object being at different points. Existence in multiple states is called superposition, and the relationships among these states is called entanglement.
• The higher the number of qubits, the higher the amount of information stored in them. Compared to the information stored in the same number of bits, the information in qubits rises exponentially. That is what makes a quantum computer so powerful.
• Building reliable quantum hardware is challenging because of the difficulty of controlling quantum systems accurately.
• Quantum machines look nothing like a regular computer. They are large cylinders of metal and twisted wires that are dropped into stainless steel refrigerators. Information is sent to the machine, as is to a traditional computer chip, and calculations are received in return.

Future of quantum computing

• Huge investment: Many tech companies including Microsoft, Intel and IBM as well as Google, are competing amongst each other for a position in quantum computing. Venture capitalists have invested millions into start-ups exploring this technology.
• Big data and Analytics: We produce 3 exabits of data every day. With classical computers reaching their limits of processing power, quantum computers can be used to spot unseen patterns in large data sets, integrate data from different data sets, and tackle the whole problem at once.
• Artificial Intelligence: Quantum machines can offer a significant leap in artificial intelligence (AI), offering quick feedbacks and making AI more intuitive.
• National Security: Governments of the US and China consider quantum computing a national security priority because it can provide encryptions that protect computers vital to national security.
• Commercial solutions: Quantum machines have potential to solve significant commercially relevant problems.
• Improved encryption: They are capable of working out the prime numbers that, multiplied together, make up an exceedingly large number – this forms basis of cryptographic protocols.
• Unhackable communication links: Quantum computers can help improve cryptography with methods like ‘quantum key distribution’, where even if the message gets intercepted, no one can read it.
• Medicine: They can aid in creation of new medicines by reviewing multiple molecules simultaneously, quickly sequencing individual DNAs for personalized drugs.
• New materials: With quantum computing new materials can be developed.
• Accurate weather forecasting: They can aid in weather forecasting and, more importantly, climate-change predictions.

Critique

• Costly: Right now, a single quantum machine costs millions of dollars to build.
• Fragile: Quantum computers are highly sensitive to environmental noise — including everyday phenomena such as temperature changes and electromagnetic fields.
• Not fully ready yet: A lot of work needs to be done before quantum computers can migrate out of the research lab.
• Supremacy overrated: Some companies have disputed the absolute dominance of quantum computers over classical computers. According to them, Google’s calculations can be performed by a traditional computer in less than 2.5 days — not 10,000 years.
• Threat to online banking: The use of quantum computing has the ability to break encryption codes and can impact online banking. But if such technological breakthroughs were to pose a real threat, it is likely that banks will themselves harness quantum computers for better protection.
• Public blockchains under threat: It was no coincidence that Bitcoin’s price slumped the day Google announced its breakthrough. The security of every ‘public blockchain’ can be under threat from quantum hacks.