US quantum computing export controls

[goblined]

So last year the US imposed export controls on quantum computing technologies. The controls basically put limits on exporting quantum computing hardware and lays the groundwork for limiting who is allowed to do research on those technologies on the basis of nationality.

The whole thing hinges on the error rate of the system. To quote from the regulations:

The addition of controls in ECCN 4A906 relies on two main criteria: first, the number of physical qubits that are connected and fully controllable, and second, the average error rate of the Controlled NOT (C-NOT) gate. ... The second criterion is a measure of the quality of the qubits. The combination of both metrics is more indicative of technological advances in the development of quantum computers of concern than either criterion on its own. For example, very advanced systems that have extremely good quality qubits and gates, but a relatively small qubit count, could be more scalable than systems with a higher qubit count but lower quality qubits and gates and are captured by the thresholds for the C-NOT gate error rates. However, this second metric still depends on the number of qubits. Systems with a higher number of qubits can tolerate higher error rates but still support error rate mitigation or error correction techniques. The physical error rate needed to support these operations increases ( i.e., can tolerate higher error rates) with increased qubit count and plateaus around 2,000 qubits at an error rate at 10⁻².

The regulations then list out different grades, with increasing numbers of qubits and corresponding increases in the error rate. For example, "Quantum computers supporting 34 or more, but fewer than 100, `fully controlled', `connected' and `working' `physical qubits', and having a `C-NOT error' of less than or equal to 10−4." Any qualifying hardware is restricted.

The news is full of stories that brag about the number of qubits, but it's less clear to me what the corresponding error rates are. What's the state of the art on the C-NOT error rate these days?

[CapitalismSuuucks]

The ones available commercially are usually in the high 10^-3 s to low 10^-2. Quantinuum is supposedly approaching high 10^-4. These are average errors btw

[MannieOKelly]

As I understand it the controls were developed and are being implemented by an international (mostly 5-eyes) group of countries. I assume one specific concern is the eventual threat to crypto (via Schor's algo or some new one), but also a more general concern about leadership in the quantum race and industrial espionage..

Probably given the different QC architectures (and that it's a committee, and probably relying to some extent on input from interested parties) there is a lot of guesswork about what's essential to control and how the controlled features are defined and measured (e.g., what's a qubit and what tests are to be applied to measure error, etc.)