Helical nanostructures – growth, cooperative & anisotropic electronics/optics in the PT-violating regime (Prof. Krstić)
Helical systems such as (nano)helices violate parity reversal symmetry (P). They represent non-linear systems with electromagnetic response functions that depend on a magnetic field vector (breaking of time reversal symmetry T). That is, their response function has spatial dispersion and (magnetic) anisotropy. Consequently, the electronic and optical properties of chiral (P-violating) systems in magnetic fields are nonlinear and anisotropic.
Furthermore, such structures can in principle have exhibit field-controlled metal to insulator transitions and (topological) charge order effects. They are prototypes of quantum optical systems for second harmonic generation, for the generation of entangled quantum states and also represent a photonic topological material. In terms of applications, such structures can be used, for example, as optical isolators or negative refractive index material.
Interestingly, the physics of such helical systems can be mapped (at least in part) to the same physics of other PT-violating systems, for example to chiral Weyl fermions exposed to an electromagnetic field or to phenomena in axion electrodynamics.
We grow nanohelix systems from different materials (Ge, Si, Ni, Ag) and achieve characteristic structural parameters < 100 nm, which leverage such nanohelix systems into the quantum regime. We investigate the properties of the nanohelix systems by means of electrical transport and optical methods in regard of PT-violation consequences and quantum-cooperative properties.
We study quantum cooperative effects in the linear and nonlinear optical response of helical metafilms. In particular, by tuning the characteristics of the metafilms, we aim to obtain a high value of the second-order nonlinear susceptibility. This property will be used to efficiently generate entangled photon pairs through spontaneous parametric down-conversion. Further, we will spatially modulate the properties of the metafilms, to vary and control the entanglement of the photon pairs, in particular in orbital angular momentum.
- Maria Chekhova
- Vojislav Krstic
- Caridad JM., Tserkezis C., Santos JE., Plochocka P., Venkatesan M., Coey JM., Mortensen NA., Rikken GL., Krstic V.:
Detection of the Faraday Chiral Anisotropy
In: Physical Review Letters 126 (2021), Article No.: 177401
- Caridad JM., Winters S., Mccloskey D., Duesberg GS., Donegan JF., Krstic V.:
Control of the plasmonic near-field in metallic nanohelices
In: Nanotechnology 29 (2018), Article No.: 325204
- Krstic V., Caridad JM., Winters S., Mccloskey D., Duesberg GS., Donegan JF., Krstic V.:
Hot-Volumes as Uniform and Reproducible SERS-Detection Enhancers in Weakly-Coupled Metallic Nanohelices
In: Scientific Reports 7 (2017), Article No.: 45548
- Krstic V., Gough JJ., McCloskey D., Caridad JM., Krstic V., Muller M., Gaponik N., Bradley AL.:
Chiral Ag Nanostructure Arrays as Optical Antennas
2015 9th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics (METAMATERIALS) (Oxford, UK)
- Caridad JM., McCloskey D., Donegan JF., Krstic V.:
Controllable growth of metallic nano-helices at room temperature conditions
In: Applied Physics Letters 105 (2014), Article No.: 233114