Fig. 2: Entanglement between on-resonance driven arbitrary spin states.
From: Entangling gates on degenerate spin qubits dressed by a global field
SWAP oscillations during (a) no microwave drive, b continuous wave microwave of duration TMW = 2.0 μs with ΩR = 1 MHz, and (c) sinusoidal modulated microwave of duration \({T}_{{{\rm{MW}}}}={T}_{{{\rm{mod}}}}=1.8\,\mu {{\rm{s}}}\). The microwave is applied along the x-axis and the modulation is according to \(\sqrt{2}{\Omega }_{{{\rm{R}}}}\cos \left(2\pi {{T}_{{{\rm{mod}}}}}^{-1}t\right)\). d–f Initialisation of arbitrary states between \(\left\vert \downarrow \uparrow \right\rangle\) and \(\left\vert \uparrow \downarrow \right\rangle\) where θ is the rotation angle of the projection pulses and VJ1 = 0.1 V. The state of the spins after the initial projection is X\((\theta )\otimes {{\rm{X}}}(\theta )\left\vert \downarrow \uparrow \right\rangle\). In (g)–(i), the traces at θ = π/2 (\(\left\vert y\right\rangle \otimes \left\vert \bar{y}\right\rangle\) initialisation) are plotted and fitted, the solid line fits the theorised spin dynamics (see Supplementary Note 6) and dashed line fits an exponential decay of the in-phase SWAP oscillations. All data is acquired in an interleaved manner. At zero time P↓↑ ≠ 1 for all VJ1, despite \(\left\vert \downarrow \uparrow \right\rangle\) initialisation, due to bandwidth limitations of the cables causing exchange interaction during the ramp.
