Imperfect Clocks Limit Quantum Computers

Just or mostly hype or a serious conundrum? Pushing fundamental limits! Another challenge for human ingenuity!

It reminds me of the Heisenberg Uncertainty Principle.

"The quantum computers that IBM, Google, Amazon, and others are developing face daunting challenges on the road to practical applications. Now it turns out that they may face a fundamental limit to large-scale performance—the imperfect nature of all clocks. ...

Prior work found that timing errors could disrupt individual quantum gates. In the new study, the scientists explored how imperfect timekeeping might impact quantum algorithms made up of a series of quantum gates. ...

A key factor in quantum-computing performance is coherence time, which is the amount of time it takes for the quantum effects that quantum computers depend on to vanish due to disruptions from the outside world ... Currently, quantum computers possess limited coherence time in which to execute quantum gates. ..."

From the abstract:

"In order to unitarily evolve a quantum system, an agent requires knowledge of time, a parameter that no physical clock can ever perfectly characterize. In this Letter, we study how limitations on acquiring knowledge of time impact controlled quantum operations in different paradigms. We show that the quality of timekeeping an agent has access to limits the circuit complexity they are able to achieve within circuit-based quantum computation. We do this by deriving an upper bound on the average gate fidelity achievable under imperfect timekeeping for a general class of random circuits. Another area where quantum control is relevant is quantum thermodynamics. In that context, we show that cooling a qubit can be achieved using a timer of arbitrary quality for control: timekeeping error only impacts the rate of cooling and not the achievable temperature. Our analysis combines techniques from the study of autonomous quantum clocks and the theory of quantum channels to understand the effect of imperfect timekeeping on controlled quantum dynamics."

Imperfect Clocks Limit Quantum Computers - IEEE Spectrum Timing issues could produce critical problems as quantum computers get bigger

Impact of Imperfect Timekeeping on Quantum Control (no public access)

The Impact of Imperfect Timekeeping on Quantum Control (open access)