Quantum optimal control
Shaping control pulses that drive a quantum system to a target state.
Quantum optimal control is the problem of finding a time-dependent control field — a pulse — that steers a quantum system from an initial state to a desired one, or that realises a target unitary operation, as accurately as possible. It underlies pulse design in nuclear magnetic resonance, quantum computing gate calibration, and quantum sensing.
The dominant practical method is gradient-based. GRAPE discretises the pulse in time and ascends the gradient of a fidelity functional with respect to each control amplitude. Because the dynamics are known, the gradient can be computed efficiently, and the same machinery extends to constraints on power, bandwidth, and robustness.
The quantum-control studio treats pulse optimisation as a reproducible computation with an explicit fidelity claim, so a reported result is tied to the conditions and the target it was optimised for rather than quoted in isolation.
The vocabulary of the topic.
- Control pulse
- The time-dependent field that drives the system; the variable being optimised.
- GRAPE
- Gradient Ascent Pulse Engineering — the standard gradient method for pulse design.
- Fidelity
- How closely the achieved state or operation matches the target; the objective being maximised.
- Target unitary
- The operation the control is designed to realise, e.g. a quantum logic gate.
Studios working on this.
Each runs standalone in its own repository and federates its evidence through the platform.
Run it, don't take it on faith.
The runnable lessons and sealed measurements this site ships for the topic.
Read it at source, in order.
Canonical references for the topic, ordered from the foundations to current work. Every one was verified at source — a DOI resolves through doi.org, a standard through its issuer — so each link goes to the real record.
Start with the foundations
- 1
A tutorial review of optimal control for quantum systems.
How it works
- 2
GRAPE — the gradient-ascent pulse-engineering algorithm.
Current work
- 3
A community survey of quantum optimal-control methods and applications.
Related topics.
Where this topic connects to the rest of the federation's work.