Article
Extended Data Fig. 7 | Relaxation, dephasing and coherence times. We
perform a Ramsey experiment, in which two π/2 pulses are separated by time τ,
during which the qubit will evolve as a result of the implemented detuning. We
fit the decay of the observed oscillations to ΔIaSD=cos(2πΔfτ+)φτexp[−(/T 2 )α],
with a a scaling factor, Δf the detuning and φ a phase offset, and find a spin
coherence time of T2,Q1=8 33 ns and T2,Q2=4 19 ns and decay coefficients of
αQ1=1.2±0.2 and αQ2=1.5±0.2, for Q1 and Q2, respectively. The spin coherence
can be extended by performing a Hahn echoing sequence, consisting of π/2, π
and π/2 pulses separated by waiting times τ. Fitting the observed decay as a
function of the total waiting time 2τ to a power law ΔIaSD=exp[−(2τT/*)]αH
2 ,
we find extended coherence times of T2,HQ1=1.9μs and T2,HQ2=0.8μs and
decay coefficients of αQ1H=1.5±0.1 and αQ2H=2.5±0.3, for Q1 and Q2, respectively.
Finally, we perform a measurement of the spin lifetime by applying a single π
pulse, after which we wait for a time τ. We fit the decay to ΔIτSD=exp[−(/T 1 )] and
find lifetimes of T1,Q1 = 9 μs and T1,Q2 = 3 μ s.