There are some obvious big picture issues that stand between us and useful quantum computing. Issues like whether we can make enough high-quality hardware qubits to connect into the error-corrected logical qubits we need, and how we generate the states needed to perform universal computation on those logical qubits. But there are also many less prominent challenges that will need to be solved before we can perform calculations.

One of those challenges, which only affects some types of hardware, is calibration. For devices we manufacture, like superconducting qubits, there are always subtle variations among individual qubits. (This is not true when we use something like an atom to hold the qubit, but the lasers that control them can drift.) As a result, this hardware is put through a process called calibration, where we test different frequencies and amplitudes of the microwave pulses that control them to find the combination that produces the lowest error rates, and then save those settings for use in calculations.

However, you can't perform the typical calibration process while you're doing calculations, which means drift becomes an issue for long and complicated algorithms. Google, though, has figured out that it's possible to do calibration using the same data that's used for error correction.

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Researchers investigate how quantum time flow can be stretched, blurred, or even reversed. What if the direction of time isn’t as fixed as it seems? While our everyday experience tells us that time moves relentlessly forward, the microscopic laws governing quantum systems are far less restrictive. In fact, many of the equations of quantum mechanics [...]

A quantum “mini universe” made from ultracold atoms revealed that time can emerge from entropy changes inside a system, offering experimental insight into one of physics’ deepest mysteries. A scientist at the University of Birmingham has created a “mini universe” that could help answer one of science’s most fundamental questions: What is time? In a [...]

It's just weird.

Quantum computing news usually picks up near the end of the year, as companies try to provide evidence that they are hitting benchmarks on time. However, there have been interesting announcements as the summer starts this year, from incremental progress to attention-grabbing promises. As we did earlier this month, Ars has a rundown of some of the most significant announcements.

These include a promise of useful, error-corrected quantum computing as soon as 2028, details on an updated trapped ion processor, and a case in which claims of quantum supremacy have been cut back a bit thanks to advances in more traditional algorithms.

2028 is remarkably soon

Many people in the field expect that useful quantum computers are still about five to 10 years away. While there may be a few useful algorithms that can be run on existing error-prone hardware, almost all of the interesting problems that quantum computing can be applied to will require some form of error correction enabled by linking a small collection of hardware qubits together into what's called a logical qubit. Logical qubits include the redundant storage of information along with neighboring qubits that can be measured to determine when errors occur and how to fix them.

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Quantum computing news usually picks up near the end of the year, as companies try to provide evidence that they are hitting benchmarks on time. However, there have been interesting announcements as the summer starts this year, from incremental progress to attention-grabbing promises. As we did earlier this month, Ars has a rundown of some of the most significant announcements.

These include a promise of useful, error-corrected quantum computing as soon as 2028, details on an updated trapped ion processor, and a case in which claims of quantum supremacy have been cut back a bit thanks to advances in more traditional algorithms.

2028 is remarkably soon

Many people in the field expect that useful quantum computers are still about five to 10 years away. While there may be a few useful algorithms that can be run on existing error-prone hardware, almost all of the interesting problems that quantum computing can be applied to will require some form of error correction enabled by linking a small collection of hardware qubits together into what's called a logical qubit. Logical qubits include the redundant storage of information along with neighboring qubits that can be measured to determine when errors occur and how to fix them.

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© QuEra

Bird flocks, bacterial swarms, and even crowds move according to interaction rules that appear to break one of physics’ most fundamental principles: Newton’s law of action and reaction. Birds can see much of what is happening around them, but when flying in a flock, they respond only to birds beside them or ahead of them. [...]

Oxford physicists have created an unconventional class of quantum superpositions from highly nonclassical states. Researchers at the University of Oxford have created a new class of quantum superpositions, including Schrödinger’s cat-like states, using building blocks that are themselves strongly nonclassical. The advance could support future quantum computing architectures based on more complex systems than conventional [...]

With dozens of companies, from small startups to tech giants, pursuing quantum computing, there's a steady flow of results as they try to find a path to utility. We typically focus on new technologies and major landmarks, which can obscure the fact that any big success will inevitably have been built on a lot of incremental progress.

The past few weeks have seen two companies release progress reports on how they're trying to get the technologies closer to general use. None of these represents a major breakthrough, but all are absolutely necessary for the technology to advance. The idea here is to convey the hard work required to move us closer to something useful.

Microsoft does material science

Microsoft is one of the few companies working on topological qubits, based on the distinct physics that occurs when particles are confined. Microsoft's system relies on a thin superconducting wire placed on top of a semiconductor. In superconductors, groups of two electrons form Cooper pairs. But if the wire contains an odd number of conducting electrons—meaning there's a single unpaired electron—it will end up delocalized to both ends of the wire. (Because quantum mechanics is weird.)

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© John Brecher for Microsoft

The big bang has causality issues, particularly the "horizon problem." I critique suggested solutions like cosmic inflation and negentropy, arguing that they require unproven concepts. The Creator, as described in the Bible, provides a coherent explanation without causality violations, in contrast with those scientific storytelling fairy tales for adults.

A new theoretical study suggests that black holes may never completely disappear, potentially offering a way to resolve the long-standing black hole information paradox. One of the biggest unsolved problems in modern physics, known as the “black hole information paradox,” may finally have a compelling solution. The proposed answer could also help explain where the [...]

Comment on PBS Space Time video PBS Space Time produces some very good videos on the foundations of quantum mechanics (QM), so let me comment on their video What If Physics IS NOT Describing Reality to provide (crucial) missing information. This comment pertains only to the first 9 min of the video, i.e., it has...

The concept of quantum superposition (or superposition for short) is very counterintuitive, as Schr##\ddot{\text{o}}##dinger noted in 1935 writing [1], “One can even set up quite ridiculous cases.” To make his point, he assumed a cat was closed out of sight in a box with a radioactive material that would decay with 50% probability within an...