PhD position: Using quantum microscopy to image the phase of a nanoscale magnetic field

Electron spins can be prepared such that they are simultaneously sensitive to the amplitude, frequency and phase of some magnetic field that we wish to investigate. In our research, such magnetic fields are due to the currents in interesting 2D electronic materials/devices. We wish to know about the conduction of charges and spins in these electronic materials/devices. The phase is particularly important as it allows us to measure the lag of the material’s response to the applied field, i.e. the complex material properties (e.g. χ’+iχ’’). Knowing the complex material properties allows for the lossy components to be separated. Combined with imaging, lossy regions of the materials can be spatially examined.

The quantum microscope in our lab uses the electron spin qubits from optical defects in diamond (NV centres) as sensors. Their spin-dependent optical dynamics allow us to directly image the effect of magnetic fields on the spin. By applying quantum control protocols to the sensor spins, we can ensure the phase of the applied field is extracted [1]. Such phase could be encoded in the Larmor precession (off-resonant) or the Rabi flopping (resonant) rotation of the spin qubit vector around the Bloch sphere.

In this project, you will use Bloch sphere descriptions of two-level quantum systems and spin-Hamiltonians to describe the NV electron spin, learn about electron spin resonance (ESR), high-resolution optical microscopy, microwave engineering and data analysis of hyperspectral images.

[1] [1] K. Mizuno, H. Ishiwata, Y. Masuyama, et al. Simultaneous wide-field imaging of phase and magnitude of AC magnetic signal using diamond quantum magnetometry. Sci Rep 10, 11611 (2020).