February 21, 2025
A pair of eye-catching recent announcements from Microsoft and Google have injected new excitement into the decadeslong pursuit of ultrapowerful quantum computing.
Microsoft researchers on Wednesday unveiled an approach to quantum computing that the company claimed involved the creation of a new state of matter. That followed Google in December touting its own breakthrough in quantum chip design.
Both advances were followed by a surge in quantum-related stock prices as investors bet they could speed the development of a new category of computers that could help in the discovery of drugs, among other applications.
Still, quantum computing remains in its relative infancy. A handful of startups and big tech companies are pursuing it, but industry experts say it will likely take years before practical and powerful quantum computers are widely available.
What is quantum computing?
Regular computers make computations using what are effectively on-off switches. Different arrangements of these switches—called “bits”—represent different values. They tell your computer or phone what to display on your screen, or what the correct result of a math problem is.
The number of bits that computers work with, and thus their computational power, has grown substantially over the past half-century. But quantum computers, when they come, promise to increase that power for certain types of computations to levels no binary-based device could conceivably reach.
How bits and quantum bits differ
Traditional computers use electronic circuits to store information in bits, digital zeros and ones encoded by the presence and absence of electricity. Quantum computers instead use qubits, particles such as electrons that are put in “superposition” with lasers or microwave beams. In superposition, quantum bits exist in two states—both a zero and a one—at the same time. As qubits have three quantum dimensions, physicists often use points on a sphere to represent them.
Peter Champelli/THE WALL STREET JOURNAL
Quantum computers use a different kind of bit, a so-called “qubit,” that can be on, off or somewhere in between—a combination of both. That allows a qubit to contain more information than a regular bit—and computers with many qubits to increase that exponentially—which opens up a range of new computational possibilities.
“Imagine a chip that can fit in the palm of your hand yet is capable of solving problems that even all the computers on Earth today combined could not!” Microsoft Chief Executive Satya Nadella said in a social-media post Wednesday.
Why is it a big deal?
If the quantum-computing industry’s dreams are realized, quantum computers would perform computations quickly that would have taken traditional computers eons. When Google unveiled its own quantum chip in December, it said it performed a computation in five minutes that would have taken one of today’s best supercomputers 10 septillion years (that is a 10 followed by 24 zeros).
A superpowerful quantum computer could perform complex simulations of the physical world with an accuracy and speed previously unheard of. The industry’s backers say that could lead to things like better-performing batteries, more efficient chemical production and new drugs. A powerful quantum computer could also theoretically break through many of today’s data encryption techniques.
Why quantum computers are faster at solving problems
Quantum computers are faster than traditional computers for optimization problems, such as finding the more efficient options for supply chains.
(L) A traditional computer tries each combination individually. (R) A quantum computer tries all combinations at once.
Source: Google Quantum AI; Peter Champelli/THE WALL STREET JOURNAL
So are quantum computers going to crack my passwords?
Maybe. The field has progressed enough that some companies are already preparing for a day at which quantum computing can break classical encryption methods. Even Apple has prepared iMessage for a post-quantum world. Some of this is based on an expectation that encrypted data can be stored in order to use quantum computing to crack it in the future.
The government has done work on replacing current forms of encryption with post-quantum algorithms, something that could be vital to national security. Despite the preparation, this isn’t something that would happen soon. For example, researchers say a quantum device powerful enough to crack bitcoin is likely a decade or more away.
What are the challenges?
Companies have been chipping away at the challenge of quantum computing for decades. The current excitement is a combination of genuine new advances and an environment where people are hoping for a sudden, ChatGPT-like moment that could catalyze a quantum boom the way AI has done in the past two years.
But it is a testament to the still-theoretical elements of quantum technology that experts aren’t sure whether these breakthroughs mean commercially viable quantum computers are now years away, or remain a decade or more off.
The difficulties of realizing quantum computing are myriad. Start with the fact that in many quantum computers, qubits need to operate at temperatures near absolute zero—that is, below negative 400 degrees Fahrenheit.
Scaling up a quantum computer can also get very messy.
All computer chips make errors that need to be checked and fixed, but fixing errors with lots of qubits has been a particularly thorny challenge. Some recent advances, including Google’s, have claimed to address the issue, but it remains perhaps the most daunting problem for the industry. Microsoft said its quantum chip had a low error probability and it had “identified clear paths” to reduce it further.
What is a topoconductor?
To create its quantum chip, Microsoft said its researchers created the world’s first “topoconductor.” The topoconductor exploited a state of matter called “topological superconductivity” that previously only existed in theory, Microsoft said.
The technical details are complex, involving super-tiny wires cooled to near absolute zero and tuned with magnetic fields. But Microsoft said its quantum chip, called Majorana 1, was designed to scale up to a million qubits on a single chip. That is a huge number: The most advanced quantum computers today have only thousands of qubits.
Which companies are exploring quantum computing?
Tech companies exploring quantum computing include Google, Microsoft and IBM, which helped pioneer the industry about a decade ago. The investment and research efforts at these companies span decades and across numerous CEOs—a relative rarity for a technology that has no foreseeable returns. There are a number of smaller companies developing such computers or adjacent technologies, such as software and related algorithms.
There are a handful of listed quantum-computing-related companies: IonQ (IONQ), Quantum Computing (QUBT), D-Wave Quantum (QBTS) and Rigetti Computing (RGTI). Many of their stock prices rose after Microsoft’s breakthrough announcement. D-Wave was up more than 7% midday on Thursday, and Rigetti was up nearly 4%.
The shares of these companies can be volatile, however. They fell sharply last month when Nvidia CEO Jensen Huang played down the utility of the technology in the near term.
“If you kind of said 15 years for very useful quantum computers, that’d probably be on the early side. If you said 30, [it] is probably on the late side,” Huang said.
LINK: https://www.wsj.com/tech/what-is-quantum-computing-explained-75c34d6e