title: Engineered micro- and nanoscale diamonds as mobile probes for high-resolution sensing in fluid.
abstract: The nitrogen-vacancy (NV) center in diamond is an attractive platform for quantum information and sensing applications because of its room temperature operation and optical addressability. A major research effort focuses on improving the quantum coherence of this defect in engineered micro- and nanoscale diamond particles (DPs), which could prove useful for high-resolution sensing in fluidic environments. In this work we fabricate cylindrical diamonds particles with finely tuned and highly reproducible sizes (diameter and height ranging from 100 to 700 and 500 nm to 2 μm, respectively) using high-purity, single-crystal diamond membranes with shallow-doped NV centers. We show that the spin coherence time of the NV centers in these particles exceeds 700 μs, opening the possibility for the creation of ultrahigh sensitivity micro- and nanoscale sensors. Moreover, these particles can be efficiently transferred into a water suspension and delivered to the region to probe. In particular, we introduce a DP suspension inside a microfluidic circuit and control position and orientation of the particles using an optical trapping apparatus. We demonstrate a DC magnetic sensitivity of 9 μT/√Hz in fluid as well as long-term trapping stability (>30 h), which paves the way toward the use of high-sensitivity pulse techniques on contactless probes manipulated within biological settings.
authors: Center for Spintronics and Quantum Computation, University of California, Santa Barbara , Santa Barbara, California 93106, United States.
authors: Paolo
authors: P
authors: Andrich
authors: Benjamín J
authors: BJ
authors: Alemán
authors: Jonathan C
authors: JC
authors: Lee
authors: Kenichi
authors: K
authors: Ohno
authors: Charles F
authors: CF
authors: de las Casas
authors: F Joseph
authors: FJ
authors: Heremans
authors: Evelyn L
authors: EL
authors: Hu
authors: David D
authors: DD
authors: Awschalom
keywords: Nanodiamond; long spin coherence; microdiamond; microfluidics; nanoscale sensing; nitrogen vacancy (NV) center; optical trapping