Enhancing the dipolar coupling of a $S$-$T_0$ qubit with a transverse sweet spot

Abstract

A fundamental design challenge for quantum dot spin qubits is to extend the strength and range of qubit interactions while suppressing their coupling to the environment, since both effects have electrical origins. Key tools include the ability to retune the qubits, to take advantage of physical resources in different operating regimes, and to access optimal working points, or "sweet spots," where dephasing is minimized. Here, we explore an important, new resource for singlet-triplet qubits: a transverse sweet spot (TSS) that enables (i) direct transitions between qubit states, (ii) a strong, charge-like qubit coupling, and (iii) leading-order protection from electrical fluctuations. Of particular interest is the possibility of transitioning between the TSS and symmetric operating points while remaining continuously protected. This arrangement is ideal for coupling qubits to a microwave cavity, because it combines maximal tunability of the coupling strength with leading-order noise suppression. We perform simulations with $1/f$-type electrical noise, demonstrating that two-qubit gates mediated by a resonator can achieve fidelities $>99$\% under realistic conditions. These results greatly expand the toolbox for singlet-triplet qubits.

9 pages + 4 pages of SI

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Cited by in corpus (14)

• The germanium quantum information route
• Tunable hole spin-photon interaction based on g-matrix modulation
• Hybrid superconductor-semiconductor systems for quantum technology
• Two-body Wigner molecularization in asymmetric quantum dot spin qubits
• Kondo QED: The Kondo effect and photon trapping in a two-impurity Anderson model ultra-strongly coupled to light
• Limits to Quantum Gate Fidelity from Near-Field Thermal and Vacuum Fluctuations
• Implementation of geometric quantum gates on microwave-driven semiconductor charge qubits
• Fast high-fidelity geometric gates for singlet-triplet qubits
• Charge noise suppression in capacitively coupled singlet-triplet spin qubits under magnetic field
• Dynamical second-order noise sweetspots in resonantly driven spin qubits
• Long-range two-hybrid-qubit gates mediated by a microwave cavity with red sidebands
• Robust entangling gate for capacitively coupled few-electron singlet-triplet qubits
• Sign-switching of superexchange mediated by few electrons under non-uniform magnetic field
• Universal singlet-triplet qubits implemented near the transverse sweet spot