Session S19: New Opportunities in Spin Sensing, Manipulation and Resonance without Time-Varying Magnetic Fields

Quantum Spin Systems in Classical Electronic Devices

The neutral divacancy (VV0) in silicon carbide (SiC) combines the advantages of a long lived spin system [1] and a near-infrared spin-photon interface [2] in a material compatible with state-of-the-art CMOS type fabrication techniques. Here, we use this scalable material to demonstrate a flexible quantum platform built by integrating and isolating single divacancies in a p-i-n diode structure.

This simple integration allows us to reduce electrical noise by engineering the defect’s environment using charge depletion. This technique effectively eliminates spectral diffusion leading to optical linewidth narrowing approaching the transform limit. Broadly, this method could be generalized to produce ideal quantum emitters in various electrically “noisy” host materials. Additionally, field confinement in the junction enables wide tuning of the optical lines by almost a terahertz. Since this field is applied along the symmetry axis, the orbital splitting and associated mixing can be minimized. Finally, using electric fields and optical excitation, we show a method for deterministic charge state control of the divacancy.

Overall, we present a narrow, widely tunable and stable spin based single photon source ideal for communication networks and long-distance entanglement. These results demonstrate the power in combining highly coherent quantum spin system with scalable classical electronics.

Related publication:
C. P. Anderson* and A. Bourassa* et al., Science (2019) [arXiv:1906.08328]
Other References:
[1] K. C. Miao et al., Science Advances (2019) [arXiv 1905.12780]
[2] D. J. Christle et al., PRX 7, 021046 (2017)

This work was peformed in collaboration with C. P. Anderson, K. C. Miao, G. Wolfowicz, P. J. Mintun, A. Crook, H. Abe, J. U Hassan, N. T. Son, T. Oshima, and D. D. Awschalom   

Spin Dependent Recombination and Variable Range Hopping in the Absence of an Oscillating Magnetic Field in Inorganic Materials and Devices

We have investigated changes in current dominated by spin dependent recombination and spin dependent variable range hopping [1-3] in a variety of systems resulting from the application of relatively small magnetic fields. We compare the current changes resulting from the small magnetic fields to current changes induced by electrically detected magnetic resonance. Magnetic fields of order one mT can yield significant current changes in silicon and silicon carbide based metal oxide semiconductor (MOS) field effect transistors (MOSFETs), bipolar junction diodes and transistors, pin diodes, MOS gated diodes, amorphous silicon nitride, amorphous silicon dioxide and amorphous carbon thin films. These near zero magnetic field induced changes are easily observable at room temperature. The near zero magnetic field response is invariably a strong function of bias applied to the device structures; both the overall amplitude of the response and the “shape” of the response can be strongly influenced by the biasing conditions. In some cases one may also apply a time dependent biasing waveform to explore the kinetics of charge capture events. In this presentation I will discuss the potentially rich source of information about electronic transport which these electron spin based measurements can provide.
(Work done in collaboration with M. Flatte, U of Iowa, N. Harmon, U of Evansville, C.J. Cochrane, JPL/Cal Tech and others.)
1. J.P. Ashton et al. IEEE Trans NS. vol. 66,428 (2019)
2. M.A. Anders et al. J. Appl. Phys. vol. 122234503 (2017)
3.M.J. Mutch et al. Appl. Phys Lett. vol. 109062403 (2016)   

Magnetoresistance Measurements as an Alternative to Magnetic Resonance Methods for Studying Paramagnetic Defects

Magnetic resonance methods such as electronic paramagnetic resonance and other companion methods like electrically detected magnetic resonance have been popular for studying unpaired spins in a wide array of materials. In some situations resonance methods are not feasible — for instance when a system of interest is beneath conductive layers as in three-dimensional integrated circuits.

Recently an alternative approach to probing paramagnetic spins was devised which does not require any electromagnetic resonant field but instead magnetoresistance is measured near zero field [1]. The magnetoresistance arises from correlations between spin pairs that involve either a carrier recombining at a trap or hopping through a trap [2]. This magnetoresistance method can be used in electronic devices to great advantage by probing paramagnetic defect environments such as hyperfine and spin-orbit couplings. A theoretical description of the magnetoresistance effect utilizes a multi-spin stochastic Liouville equation [3] which provides agreement with recombination currents in MOSFETs. For high-nuclear spin defects, the theory predicts new resonances in the magnetoresistance that provide precise determination of hyperfine constants. These results offer a new means of analysis which does not rely on a resonator and are potentially applicable to systems inaccessible to conventional resonance methods.

This work was done in collaboration with the groups of M. E. Flatté (U of Iowa ) and P. A. Lenahan (Penn. State U).

[1] J. Ashton et al, IEEE Trans. on Nucl. Sci. 66, 428 (2019)
[2] J. Rybicki et al, Phys. Rev. Lett. 109, 076603 (2012)
[3] Y. Wang et al, Phys. Rev. X 6, 011011 (2016)   

Quantum acoustic control of diamond nitrogen-vacancy centers

Here we report on diamond mechanical resonator device engineering and its application to the acoustic control of NV center quantum states. We fabricate high quality diamond bulk acoustic resonators with gigahertz modes and integrated NV centers. Driving the resonator creates direct coupling of phonons to NV center electron spin and orbital states. At room temperature, we observe both single and double quantum spin transitions driven by phonons. Through improved device engineering, we demonstrate efficient acoustic control of NV center spin states using a semi-confocal high over-tone resonator. At cryogenic temperature, we probe the orbital states of a single NV center using photoluminescence excitation (PLE) spectroscopy. We show that the effects of phonon driving are spectroscopically revealed as Autler-Townes splitting and the occurrence of Raman sidebands. Lastly, we discuss how mechanical driving can be leveraged for decoherence protection based on phonon-dressed NV electronic states.

[1] H. Y. Chen, et al., Phys. Rev. Lett. 120, 167401 (2018).
[2] H. Y. Chen, et al., Nano. Lett. 19,10, 7021-7027 (2019).

In collaboration with N. F. Opondo, B. Jiang, E. R. MacQuarrie, R. S. Daveau, S. A. Bhave and G. D. Fuchs.
  

Nonlinear planar Hall effect

An intriguing property of a three-dimensional (3D) topological insulator is the existence of surface states with spin-momentum locking, which offers a new frontier of exploration in spintronics. Here, we report the observation of a new type of Hall effect in a 3D topological insulator Bi₂Se₃ film. The Hall resistance scales linearly with both the applied electric and magnetic fields and exhibits a π/2 angle offset with respect to its longitudinal counterpart, in contrast to the usual angle offset of π/4 between the linear planar Hall effect and the anisotropic magnetoresistance. This novel nonlinear planar Hall effect originates from the conversion of a nonlinear transverse spin current to a charge current due to the concerted actions of spin-momentum locking and time-reversal symmetry breaking, which also exists in a wide class of non-centrosymmetric materials with a large span of magnitudes. This provides a new way to characterize and utilize the nonlinear spin-to-charge conversion in a variety of topological quantum materials.