Sub-nm-spaced frequency-addressed qubits

The proximity between the ions results in large interactions and potentially allows fast gates, but they can still be separately addressed since different ions have different optical resonance frequency. The interaction that enables multi-qubit gates can be turned on at will and is based on that the permanent dipole moment changes as a control ion is transferred to the optically excited state which in turn Stark-shifts target qubit out of resonance. Using optical pumping, all ions within a frequency interval can be removed and then a peak of equivalent ions, each belonging to one instance of many parallel quantum computers can be positioned within the non-absorbing region. This qubit has then been efficiently transferred between different qubit states using robust complex hyperbolic secant pulses. Pairs of qubits that interact strongly have also been distilled