Diamond Materials

Diamond Materials for Quantum Application

23. September 2014: The DFG research group FOR 1493 “Diamond Materials and Quantum Applications” goes into its second funding period. FOR1493 is a national research consortium funded by the Deutsche Forsch-ungsgemeinschaft.

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ERC Advanced Grant


Controlled Spin-Phonon Interactions in Diamond

Heralded Control of Mechanical Motion by Single Spins

We propose a method to achieve a high degree of control of nanomechanical oscillators by coupling their mechanical motion to single spins. Manipulating the spin alone and measuring its quantum state heralds the cooling or squeezing of the oscillator even for weak spin-oscillator couplings. We analytically show that the asymptotic behavior of the oscillator is determined by a spin-induced thermal filter function whose overlap with the initial thermal distribution of the oscillator determines its cooling, heating, or squeezing. Counterintuitively, the rate of cooling dependence on the instantaneous thermal occupancy of the oscillator renders robust cooling or squeezing even for high initial temperatures and damping rates. We further estimate how the proposed scheme can be used to control the motion of a thin diamond cantilever by coupling it to its defect centers at low temperature.

Thin Circular Diamond Membrane with Embedded Nitrogen-Vacancy Centers for Hybrid Spin-Mechanical Quantum Systems

Coupling mechanical degrees of freedom to single well-controlled quantum systems has become subject to intense research recently. Here, we report on the design, fabrication, and characterization of a diamond architecture consisting of a high-quality thin circular diamond membrane with embedded near-surface nitrogen-vacancy centers (NVCs). To demonstrate this architecture, we employ the NVCs by means of their optical and spin interfaces as nanosensors of the motion of the membrane under static pressure and in-resonance vibration. We also monitor the static residual stress within the membrane using the same method. Driving the membrane at its fundamental resonance mode, we observe coupling of this vibrational mode to the spin of the NVCs. Our realization of this architecture can manifest the applications of diamond structures in 3D piezometry such as mechanobiology and vibrometry, as well as mechanically mediated spin-spin coupling in quantum-information science.

Heralded Control of Mechanical Motion by Single Spins
D.D. Bhaktavatsala Rao, S. Ali Momenzadeh, and Jörg Wrachtrup
Phys. Rev. Lett. 117, 077203 – Published 11 August 2016

Thin Circular Diamond Membrane with Embedded Nitrogen-Vacancy Centers for Hybrid Spin-Mechanical Quantum Systems
S. Ali Momenzadeh, Felipe Fávaro de Oliveira, Philipp Neumann, D.D. Bhaktavatsala Rao, Andrej Denisenko, Morteza Amjadi, Zhiqin Chu, Sen Yang, Neil B. Manson, Marcus W. Doherty, and Jörg Wrachtrup
Phys. Rev. Applied 6, 024026 – Published 31 August 2016