Chiral‐Plasmon‐Tuned Potentials for Atom Trapping at the Nanoscale

Abstract

Neutral atom trapping is of importance in precision quantum metrology and quantum information processing where the atom can be viewed as an excellent frequency reference. However, creating tunable optical traps compatible with the optical nanostructures is still a challenge. Here, by introducing the chiroptical effects of a plasmonic structure into atom trapping, an active tunable potential for 3D stable optical trapping at the nanoscale is demonstrated. By altering the incident light from left‐ to right‐handed circularly polarized, the tunable range of position and potential of the trapped atoms can reach ≈60 nm and ≈0.51N mK (N denotes input power with unit mW), respectively. In addition, the blue‐detuned circularly polarized light guarantees the ultralow scattering rate and ultralong trapping lifetime. The trap centers are about hundreds of nanometers away from the structure surface, which ensures the stability of the trapping system due to the ignorable surface potential. This chiral‐based tunable atom trapping system broadens the application of chiral metamaterials and has important impact on all‐optical modulation, atomic on‐chip integration, manipulation of cold atoms, and quantum many‐body systems.

Tunable atom-trapping based on a plasmonic chiral metamaterial

“…In addition, we can find that the field distributions at a(1) (point A) and a(21) (point C) are obviously different. Compared to our previous work [48], the proposed structure is relatively compact, the CD_T response is larger, and one single unit cell can realize all the features. Although the movable range of the trapped atom is similar, the tunable potential is increased by about 2.6 times, which greatly increases the practicability of the system.…”

“…According to previous literature [44,45,48], we know that the near-field scattering effect of the periodic plasmonic structure can produce a local electric field minimum in the spatial extent of the system. In our system, RCP and LCP light incidence cause different scattering intensities, which in turn make the local electric field minimum adjustable.…”

“…(It is to be noted that the electric field distributions are the same at x = 0 or y = 0 plane only when LCP or LCP light excites because of the peculiarity of the structure.) The resonant wavelength λ = 760 nm is selected to be blue-detuned to the D 2 line of 87 Rb atoms [45,48]. By the way, the proposed trapping platform is suitable for trapping neutral atoms with all the transition wavelengths greater than 760 nm, e.g.…”

Plasmon-Induced Transparency for Tunable Atom Trapping in a Chiral Metamaterial Structure

“…Neutral atom trapping plays a vital role in quantum computing and data storage. The minimum value of the local electric field generated by the near-field scattering effect of periodic surface plasmons is the best region to realize the atom trapping with detuned blue light [33][34][35]. Herein, we first unite the PIT phenomenon with atom trapping through the structure proposed in Figure 1a and discuss in detail the PIT effect on the trapping characteristics of neutral atoms.…”

Gold cauldrons as efficient candidates for plasmonic tweezers

“…The other drawback of OT is the bulky external optical equipment of light focusing, which hinders the size reduction of the related optophoresis systems and the ability to realize lab-on-a-chip (LOC) devices. On the other hand, plasmonic tweezers, benefiting from inherent highly confined and strongly enhanced local electromagnetic field, has been attracted numerous researchers for trapping, sorting, separation and sensing of particles 7 , 8 . Plasmonic tweezers take advantage of the strong plasmonic field gradient at the vicinity of the metal/dielectric interface, leading to a strong gradient force at a lower laser power and without the need for light focusing equipment.…”