Temperature Dependence of Spin Relaxation and Charge Noise in Silicon Spin Qubits

Large-scale quantum computing is pursued by a wide variety of scientific disciplines. While leading solid-state approaches focus on decreasing the operation temperature to almost zero Kelvin, a crucial question is if the available cooling power will then be sufficient to increase the number of qubits to the required thousands or millions.
Here, we work towards hot-qubits, using electron spins in silicon quantum dots, and characterize the temperature dependence of the spin relaxation time and the charge noise. We have fabricated quantum dot devices on isotopically purified silicon that can host up to four qubits in a linear array. We deplete one quantum dot to the single-electron regime and we are able to readout the spin state in single shot mode. We map out the magnetic field and temperature dependence of the spin lifetime, measuring T₁ times larger than 1 ms beyond 1 K. From the temperature dependence study we conclude that the relaxation rate at high temperatures is determined by two-phonon Raman transitions, rather than Orbach processes, up to 1 K. We also investigate the effect of temperature on the charge noise, measured as current fluctuations of a SET, and find consistency with a linear temperature dependence up to 4K.