The T1 time in our systems describes the decay of qubit excitation resulting from energy exchange between an ion and its environment. The T1 time is limited by the natural lifetime of the energy levels constituting the qubit system. The T2 time, on the other hand, describes the loss of coherence of a quantum system resulting from dephasing induced predominantly by laser and magnetic field fluctuations.
Physically, the ultimate limit for the T2 time of the quantum system is given by the lifetime T1 : T2 < 2*T1. In other words: a well isolated quantum system should demonstrate T2 times ‘on the order of’ T1. Here, we present the T1 and T2 time measured in the AQT MARMOT system. We first highlight the identical behaviour of each ion, exemplified by the time T1 = 1.14 +- 0.06 s, measured for each ion in a register of 20 ions. A laser linewidth of less than 1 Hz and highly stable magnetic fields provide us with an excellent T2 time between 0.5-1.2 s. Considering typical gate times on the order of 10 to 100 µs, the quantum memory persists for the equivalent of up to 1000 quantum gate operations – a feat highly challenging for other platforms.