esrΒΆ A collection of qugrad.QuantumSystem s for electron spin resonance (ESR) devices. Classes SpinChain A qugrad.QuantumSystem for a spin chain with electron spin resonance (ESR) controls. SpinChainAngledDrive A qugrad.QuantumSystem for a spin chain with electron spin resonance (ESR) controls. ValleyChain A qugrad.QuantumSystem for a linear array of silicon electron quantum dots including the valley degree of freedom and electron spin resonance (ESR) controls.