More Like this

1. Observation of an environmentally insensitive solid state spin defect in diamond

   Brendon C. Rose, Ding Huang (June 2017, arXiv.org)

   Engineering coherent systems is a central goal of quantum science. Color centers in diamond are a promising approach, with the potential to combine the coherence of atoms with the scalability of a solid state platform. However, the solid environment can adversely impact coherence. For example, phonon- mediated spin relaxation can induce spin decoherence, and electric field noise can change the optical transition frequency over time. We report a novel color center with insensitivity to both of these sources of environmental decoherence: the neutral charge state of silicon vacancy (SiV0). Through careful material engineering, we achieve over 80% conversion of implanted silicon to SiV0. SiV0 exhibits excellent spin properties, with spin-lattice relaxation times (T1) approaching one minute and coherence times (T2) approaching one second, as well as excellent optical properties, with approximately 90% of its emission into the zero-phonon line and near-transform limited optical linewidths. These combined properties make SiV0 a promising defect for quantum networks. 

   more » « less
2. Probing NV and SiV charge state dynamics using high-voltage nanosecond pulse and photoluminescence spectral analysis

   https://doi.org/10.1088/2633-4356/acf750  

   Pambukhchyan, Artur; Weng, Sizhe; Aravind, Indu; Cronin, Stephen B; Takahashi, Susumu (September 2023, Materials for Quantum Technology)

   Abstract Nitrogen-vacancy (NV) and silicon-vacancy (SiV) color defects in diamond are promising systems for applications in quantum technology. The NV and SiV centers have multiple charge states, and their charge states have different electronic, optical and spin properties. For the NV centers, most investigations for quantum sensing applications are targeted on the negatively charged NV (NV⁻), and it is important for the NV centers to be in the NV⁻state. However, it is known that the NV centers are converted to the neutrally charged state (NV⁰) under laser excitation. An energetically favorable charge state for the NV and SiV centers depends on their local environments. It is essential to understand and control the charge state dynamics for their quantum applications. In this work, we discuss the charge state dynamics of NV and SiV centers under high-voltage nanosecond pulse discharges. The NV and SiV centers coexist in the diamond crystal. The high-voltage pulses enable manipulating the charge states efficiently. These voltage-induced changes in charge states are probed by their photoluminescence spectral analysis. The analysis result from the present experiment shows that the high-voltage nanosecond pulses cause shifts of the chemical potential and can convert the charge states of NV and SiV centers with the transition rates of ∼MHz. This result also indicates that the major population of the SiV centers in the sample is the doubly negatively charged state (SiV²⁻), which is often overlooked because of its non-fluorescent and non-magnetic nature. This demonstration paves a path for a method of rapid manipulation of the NV and SiV charge states in the future. 

   more » « less
3. Photo‐Induced Charge State Dynamics of the Neutral and Negatively Charged Silicon Vacancy Centers in Room‐Temperature Diamond

   https://doi.org/10.1002/advs.202308814  

   Garcia‐Arellano, G; López‐Morales, G I; Manson, N B; Flick, J; Wood, A A; Meriles, C A (June 2024, Advanced Science)

   Abstract The silicon vacancy (SiV) center in diamond is drawing much attention due to its optical and spin properties, attractive for quantum information processing and sensing. Comparatively little is known, however, about the dynamics governing SiV charge state interconversion mainly due to challenges associated with generating, stabilizing, and characterizing all possible charge states, particularly at room temperature. Here, multi‐color confocal microscopy and density functional theory are used to examine photo‐induced SiV recombination — from neutral, to single‐, to double‐negatively charged — over a broad spectral window in chemical‐vapor‐deposition (CVD) diamond under ambient conditions. For the SiV⁰to SiV^‐transition, a linear growth of the photo‐recombination rate with laser power at all observed wavelengths is found, a hallmark of single photon dynamics. Laser excitation of SiV^‒, on the other hand, yields only fractional recombination into SiV^2‒, a finding that is interpreted in terms of a photo‐activated electron tunneling process from proximal nitrogen atoms. 

   more » « less
4. Quantum information processing with integrated silicon carbide photonics

   https://doi.org/10.1063/5.0077045  

   Majety, Sridhar; Saha, Pranta; Norman, Victoria A.; Radulaski, Marina (April 2022, Journal of Applied Physics)

   Color centers in wide bandgap semiconductors are prominent candidates for solid-state quantum technologies due to their attractive properties including optical interfacing, long coherence times, and spin–photon and spin–spin entanglement, as well as the potential for scalability. Silicon carbide color centers integrated into photonic devices span a wide range of applications in quantum information processing in a material platform with quantum-grade wafer availability and advanced processing capabilities. Recent progress in emitter generation and characterization, nanofabrication, device design, and quantum optical studies has amplified the scientific interest in this platform. We provide a conceptual and quantitative analysis of the role of silicon carbide integrated photonics in three key application areas: quantum networking, simulation, and computing. 

   more » « less
5. Photophysics of O-band and transition metal color centers in monolithic silicon for quantum communications

   https://doi.org/10.1038/s42005-025-01954-0  

   Sarihan, Murat Can; Huang, Jiahui; Kang, Jin Ho; Fan, Cody; Liu, Wei; Azizur-Rahman, Khalifa M; Liang, Baolai; Wong, Chee Wei (January 2025, Communications Physics)

   Abstract Color centers in the O-band (1260–1360 nm) are crucial for realizing long-coherence quantum network nodes in memory-assisted quantum communications. However, only a limited number of O-band color centers have been thoroughly explored in silicon hosts as spin-photon interfaces. This study explores and compares two promising O-band color centers in silicon for high-fidelity spin-photon interfaces: T and *Cu (transition metal) centers. During T center generation process, we observed the formation and dissolution of other color centers, including the copper-silver related centers with a doublet line around 1312 nm (*$${{{\rm{Cu}}}}_{n}^{0}$$ ${\mathrm{Cu}}_n^0$), near the optical fiber zero dispersion wavelength (around 1310 nm). We then investigated the photophysics of both T and *Cu centers, focusing on their emission spectra and spin properties. The *$${{{\rm{Cu}}}}_{0}^{0}$$ ${\mathrm{Cu}}_0^0$line under a 0.5 T magnetic field demonstrated a 25% broadening, potentially due to spin degeneracy, suggesting that this center can be a promising alternative to T centers. 

   more » « less