Quantum photonic networks in diamond
- PDF / 501,199 Bytes
- 5 Pages / 585 x 783 pts Page_size
- 95 Downloads / 193 Views
otivation Diamond possesses remarkable physical and chemical properties and in many ways is the ultimate engineering material, often termed “the engineer’s best friend.” It has high mechanical hardness (10,000 kg mm–2), high Young’s modulus (1050 GPa), high thermal conductivity (22 W cm–1 K–1), low thermal expansion coefficient, high breakdown field (>10 MV cm–1), and high carrier mobility (4500 cm2 V–1 for electrons and 3800 cm2 V–1 for holes).1 It is biocompatible and chemically inert. Optically, diamond is transparent from the UV to IR, has a high refractive index (n = 2.4), large Raman gain (15–75 cm GW–1),2 large intensity-dependent refractive index (n2 = 1.3 × 10–19 m2 W–1), and a wide variety of light-emitting defects.3 These properties make diamond a highly desirable material for many applications, including high-frequency microand nanoelectromechanical systems, nonlinear optics, magnetic and electric field sensing, and biomedicine (e.g., cell labeling/ monitoring, biosensing, and drug delivery). One particularly exciting application of diamond is in the field of quantum information science and technology (QIST), which promises realization of powerful quantum computers capable of tackling problems that cannot be solved using classical approaches, as well as realization of secure communication channels. At the heart of these applications is diamond’s luminescent crystalline defects—color centers—and the nitrogenvacancy (NV) color center in particular. This atomic system in
the solid-state possesses all the essential elements for QIST, including storage, logic, and communication of quantum information. Quantum information can be stored in the electron spin of the NV or the nuclear spin of nearby atoms, with very long lifetimes even at room temperature.4 Quantum logic can be achieved via the application of microwave and RF fields to drive transitions between these electron and nuclear spin sublevels.5–7 Finally, spin quantum information can be communicated via spin-dependent fluorescence intensity, resulting in a source of spin-photon entangled pairs.8 However, these and other applications depend crucially on the efficiency with which information can be exchanged between the NV center’s electron spin (a stationary qubit in the context of quantum computation) and a photon (a ‘‘flying’’ qubit). Therefore, the ability to efficiently excite the NV center and readout its spin state optically is of central importance. Unfortunately, in the case of NV centers in a bulk diamond substrate, this process is affected by the total-internal reflection at the diamond-air interface, due to the large refractive index of diamond (n = 2.4), resulting in a typical photon collection efficiency of ∼3% (Figure 1a). Moreover, the NV-photon interaction in a particular transition that is of interest for quantum information applications, the zero-phonon line (ZPL), is relatively weak compared to other photonic transitions. Therefore, there has been great interest in increasing the photon–NV center interaction using
Marko Loncˇ ar, School of Engine
Data Loading...
