Bloomberg on Quantum Computing: appeal, who’s building them, how does it work?
1. What’s the appeal of quantum computers?
They can do things that classical computers can’t. Google revealed in April that one of its quantum computers had solved a problem in seconds that would have taken the world’s most powerful supercomputer 47 years. Experimental quantum computers are typically given tasks that a conventional computer would take too long to do, such as simulating the interaction of complex molecules for drug discovery. Their greatest potential is for modeling complex systems involving large numbers of moving parts whose behavior changes as they interact — such as predicting the behavior of financial markets, optimizing supply chains and operating the large language models used in generative artificial intelligence. They’re not expected to be much use in the laborious but simpler work fulfilled by most of today’s computers — processing a more limited number of isolated inputs sequentially on a mass scale.
2. Who’s building them?
Canadian company D-Wave Systems Inc. became the first to sell quantum computers to solve optimization problems in 2011. International Business Machines Corp., Alphabet Inc.’s Google, Amazon Web Services and numerous startups have all created working quantum computers. More recently, companies such as Microsoft Corp. have made progress toward building scalable and practical quantum supercomputers. Intel Corp. started shipping a silicon quantum chip to researchers with transistors known as qubits (quantum bits) that are as much as 1 million times smaller than other types. Microsoft and other companies, including startup Universal Quantum, expect to build a quantum supercomputer within the next ten years. China is building a $10 billion National Laboratory for Quantum Information Sciences as part of a big push in the field.
3. How do quantum computers work?
They use tiny circuits to perform calculations, as do traditional computers. But they make these calculations in parallel, rather than sequentially, which is what makes them so fast. Regular computers process information in units called bits, which can represent one of two possible states — 0 or 1 — that correspond to whether a portion of the computer chip called a logic gate is open or closed. Before a
traditional computer moves on to process the next piece of information, it must have assigned the previous piece a value. By contrast, thanks to the probabilistic aspect of quantum mechanics, the qubits in quantum computers don’t have to be assigned a value until the computer has finished the whole calculation. This is known as “superposition.” So whereas three bits in a conventional computer would only be able to represent one of eight possibilities – 000, 001, 010, 011, 100, 101, 110 and 111 – a quantum computer of three qubits can process all of them at the same time. A quantum computer with 4 qubits can in theory handle 16 times as much information as an equally-sized conventional computer and will keep doubling in power with every qubit that’s added. That’s why a quantum computer can process exponentially more information than a classic computer.
Why Quantum Will Be Quicker
Problems like breaking encryption or mapping a molecule’s structure can require sorting through millions of possibilities.
4. How does it return a result?
In designing a standard computer, engineers spend a lot of time trying to ensure that the status of each bit is independent from those of all the other bits. But qubits are entangled, meaning the properties of one depend on the properties of the qubits around it. This is an advantage, as information can be transferred quicker between qubits as they work together to arrive at a solution. As a quantum algorithm runs, contradictory (and therefore incorrect) results from the qubits cancel each other out, whilst compatible (and therefore likely) results are amplified. This phenomenon, called coherence, allows the computer to spit out the answer it deems most likely to be correct.
5. How do you make a qubit?
In theory, anything exhibiting quantum mechanical properties that can be controlled could be used to make qubits. IBM, D-Wave and Google use tiny loops of superconducting wire. Others use semiconductors and some use a combination of both. Some scientists have created qubits by manipulating trapped ions, pulses of photons or the spin of electrons. Many of these approaches require very specialized conditions, such as temperatures colder than those found in deep space.
6. How many qubits are needed?
Lots. Although qubits can process exponentially more information than classical bits, their inherently uncertain nature makes them heavily prone to errors. Errors creep into qubits’ calculations when they fall out of coherence with each other. Outside the lab, scientists have only been able to keep qubits in coherence for fractions of a second — in many cases, too short a period of time to run an entire algorithm. Theorists are working to develop algorithms that can correct some of these errors. But an inevitable part of the fix is adding more qubits. Scientists estimate that a computer needs millions – if not billions – of qubits to reliably run programs suited for commercial use. Sticking enough of them together is the main challenge. As a computer gets larger in size, it emits more heat, which makes it more likely that qubits will fall out of coherence. The current record for qubits connected is 1,180, achieved by California startup Atom Computing in October 2023 — more than double the previous record of 433, set by IBM in November 2022.
7. When do I get my quantum computer?
It depends on what you want to use it for. Academics are already solving problems on 100-strong qubit machines through the cloud-based IBM Quantum Platform, which the general public is able to try out (if you know how to develop quantum code). Scientists aim to deliver a so-called “universal” quantum computer suitable for commercial applications within the next decade. One caveat of the enormous problem-solving power of quantum computers is their potential for cracking classical encryption systems. Perhaps the best indication of just how close we are to quantum computing is that governments are signing directives and businesses are pouring millions of dollars into securing legacy computing systems against being cracked by quantum machines.
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Quantum computer technologies are incredible, in that they allow for processing what would have been otherwise (essentially) impossible. And I’ve seen the interest in this hardware move from the casual to the serious recently.