arXiv subjects

X. -D. Chen

Publications and source records attributed to X. -D. Chen.

4 recordsLinked to original sources

arXiv2022

Coherent dynamics of multi-spin $\rm V_B^-$ centers in hexagonal boron nitride

Hexagonal boron nitride (hBN) has recently been demonstrated to contain optically polarized and detected electron spins that can be utilized for implementing qubits and quantum sensors in nanolayered-devices. Understanding the coherent dynamics of microwave driven spins in hBN is of crucial importance for advancing these emerging new technologies. Here, we demonstrate and study the Rabi oscillation and related dynamical phenomena of the negatively charged boron vacancy ($\rm V_B^-$) spins in hBN. We report on different dynamics of the $\rm V_B^-$ spins at weak and strong magnetic fields. In the former case the defect behaves like a single electron spin system, while in the latter case it behaves like a multi-spin system exhibiting the multiple-frequency dynamical oscillation like clear beat in Ramsey fringes. We also carry out theoretical simulations for the spin dynamics of $\rm V_B^-$ and reveal that the nuclear spins can be driven via the strong electric-nuclear coupling existing in $\rm V_B^-$ center, which can be modulated by the magnetic field and microwave field.

quant-ph↗

arXiv2020

Mapping the Galactic disk with the LAMOST and Gaia Red clump sample. VI: An evidence for the long lived non-steady warp of non-gravitational scenarios

By combining LAMOST DR4 and Gaia DR2 common red clump stars with age and proper motion, we analyze the amplitude evolution of the stellar warp independently of any assumption with a simple model. The greatest height of the warp disk increases with Galactocentric distance in different populations and it is dependent on the age: the younger stellar populations exhibit stronger warp features than the old ones, accompanied with the warp amplitude $γ({\rm age})$ decreasing with age and its first derivative $\dotγ ({\rm age})$ is different from zero. The azimuth of line of nodes $ϕ_w$ is stable at $-$5 degree without clear time evolution, which perfectly confirms some of previous works. All these self-consistent evidences support that our Galactic warp should most likely be a long lived, but non-steady structure and not a transient one, which is supporting the warp is originated from gas infall onto the disk or other hypotheses that suppose that the warp mainly affects to the gas, and consequently younger populations tracing the gas are stronger than the older ones. In other words, the Galactic warp is induced by the non-gravitational interaction over the disk models.

astro-ph.GA↗

arXiv2013

Vector magnetic field sensing by single nitrogen vacancy center in diamond

In this Letter, we proposed and experimentally demonstrated a method to detect vector magnetic field with a single nitrogen vacancy (NV) center in diamond. The magnetic field in parallel with the axis of the NV center can be obtained by detecting the electron Zeeman shift, while the Larmor precession of an ancillary nuclear spin close to the NV center can be used to measure the field perpendicular to the axis. Experimentally, both the Zeeman shift and Larmor precession can be measured through the fluorescence from the NV center. By applying additional calibrated magnetic fields, complete information of the vector magnetic field can be achieved with such a method. This vector magnetic field detection method is insensitive to temperature fluctuation and it can be applied to nanoscale magnetic measurement.

quant-ph↗

arXiv2010

Plasmon modes of silver nanowire on a silica substrate

Plasmon mode in a silver nanowire is theoretically studied when the nanowire is placed on or near a silica substrate. It is found that the substrate has much influence on the plasmon mode. For the nanowire on the substrate, the plasmon (hybrid) mode possesses not only a long propagation length but also an ultrasmall mode area. From the experimental point of view, this cavity-free structure holds a great potential to study a strong coherent interaction between the plasmon mode and single quantum system (for example, quantum dots) embedded in the substrate.

physics.optics↗