February 2025
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7 Reads
Physical Review Applied
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February 2025
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7 Reads
Physical Review Applied
January 2025
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7 Reads
November 2024
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168 Reads
High sensitivity and high quality‐factor are crucial for achieving outstanding sensing performance in photonic biosensors. However, strong optical field confinement and high light–biomolecule interactions on photonic surfaces are usually contradictory and challenging to satisfy simultaneously. Here, a distinctive configuration for addressing this issue is reported: embedding a nanophotonic metasurface inside a micro vertical cavity as a meta‐channel (metacavity) biosensor. The analyte solution serves as the cavity medium, thereby maximizing the light–analyte interaction. Simulation validation is conducted to optimize the metacavity with high structural robustness and remarkable optical and sensing properties. Large‐scale low‐cost metacavity biosensors are realized by combining anodic aluminum oxide template technique and wafer bonding. Experimentally, the metacavity biosensor demonstrates a notable quality‐factor (maximum 4140) and high bulk refractometric sensitivity (450 nm RIU⁻¹), resulting in an unprecedented figure‐of‐merit (1670 RIU⁻¹). Moreover, the metacavity biosensor achieves high surface sensitivity, together with a detection‐limit of 119 viral copies mL⁻¹ for label‐free severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) pseudovirus sensing, revealing remarkable performance in both bulk and surface sensing.
October 2024
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34 Reads
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6 Citations
Science Advances
We report on the experimental realization and characterization of a qubit analog with semiconductor exciton-polaritons. In our system, a polaritonic condensate is confined by a spatially patterned pump laser in an annular trap that supports energy-degenerate vortex states of the polariton superfluid. Using temporal interference measurements, we observe coherent oscillations between a pair of counter-circulating vortex states coupled by elastic scattering of polaritons off the laser-imprinted potential. The qubit basis states correspond to the symmetric and antisymmetric superpositions of the two vortex states. By engineering the potential, we tune the coupling and coherent oscillations between the two circulating current states, control the energies of the qubit basis states, and initialize the qubit in the desired state. The dynamics of the system is accurately reproduced by our theoretical two-state model, and we discuss potential avenues to implement quantum gates and algorithms with polaritonic qubits analogous to quantum computation with standard qubits.
July 2024
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4 Reads
April 2024
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17 Reads
August 2023
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309 Reads
We report on the experimental realization and characterization of an exciton-polariton qubit prototype. In our system, a Bose-Einstein condensate of semiconductor exciton-polaritons is confined by a spatially-patterned pump laser in an annular trap that supports energy-degenerate circulating currents of the polariton superfluid. Using non-invasive temporal interference measurements, we observe coherent oscillations between a pair of counter-circulating superfluid vortex states of the polaritons coupled by elastic scattering off the laser-imprinted potential. The qubit basis states correspond to the symmetric and antisymmetric superpositions of the two vortex states forming orthogonal double-lobe spatial wavefunctions. By engineering the potential, we tune the coupling and coherent oscillations between the two circulating current states, control the energies of the qubit basis states and thereby initialize the qubit in the desired state. The dynamics of the system is accurately reproduced by our theoretical two-state model, and we discuss potential avenues to achieve complete control over our polaritonic qubit and implement controllable interactions and quantum gates between such qubits.
March 2023
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54 Reads
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4 Citations
Transition metal dichalcogenide (TMD) monolayers (1L) in the 2H-phase are two-dimensional semiconductors with two valleys in their band structure that can be selectively populated using circularly polarized light. The choice of the substrate for monolayer TMDs is an essential factor for the optoelectronic properties and for achieving a high degree of valley polarization at room temperature (RT). In this work, we investigate the room-temperature valley polarization of monolayer WS2 on different substrates. A degree of polarization of photoluminescence (PL) in excess of 27% is found from neutral excitons in 1L-WS2 on graphite at room temperature, under resonant excitation. Using chemical doping through photochlorination we modulate the polarization of the neutral exciton emission from 27% to 38% for 1L-WS2/graphite. We show that the valley polarization strongly depends on the interplay between doping and the choice of the supporting layer of TMDs. Time-resolved PL measurements, corroborated by a rate equation model accounting for the bright exciton population in the presence of a dark exciton reservoir support our findings. These results suggest a pathway towards engineering valley polarization and exciton lifetimes in TMDs, by controlling the carrier density and/or the dielectric environment at ambient conditions.
June 2022
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32 Reads
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20 Citations
ACS Photonics
January 2021
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152 Reads
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1 Citation
Gain and loss modulation are ubiquitous in nature. An exceptional point arises when both the eigenvectors and eigenvalues coalesce, which in a physical system can be achieved by engineering the gain and loss coefficients, leading to a wide variety of counter-intuitive phenomena. In this work we demonstrate the existence of an exceptional point in an exciton polariton condensate in a double-well potential. Remarkably, near the exceptional point, the polariton condensate localized in one potential well can be switched off by an additional optical excitation in the other well with very low (far below threshold) laser power which surprisingly induces additional loss into the system. Increasing the power of the additional laser leads to a situation in which gain dominates in both wells again, such that the polaritons re-condense with almost the same density in the two potential wells. Our results offer a simple way to optically manipulate the polariton lasing process in a double-well potential structure. Extending such configuration to complex potential well lattices offers exciting prospects to explore high-order exceptional points and non-Hermitian topological photonics in a non-equilibrium many-body system.
... 12 Recently, polaritonic qubits have been generated for the realization of quantum gates and algorithms, analogous to quantum computation with standard qubits. 13,14 Flexibly creating and manipulating exciton polaritonic states with specific energy and momentum is crucial for applications in photonics and quantum technologies. 15,16 The tunable momentum of polaritons introduces more allowed scattering processes in reciprocal space, in which polaritons can participate, facilitating the directional control of radiation and other scattering processes. ...
October 2024
Science Advances
... 15 and 24) In addition, this process assists in sustaining large degrees of VP at room temperature. 25 Finally, after following a quality assessment procedure, incorporating lPL, and reflectance experiments, the complete heterostructure is encapsulated in poly-methyl methacrylate (PMMA, Microchem) and transferred on top of an elastic substrate with a cruciform shape (see detailed methodology in the supplementary material, Sec. A, Fig. S1). ...
March 2023
... The selection of examples is designed to illustrate the capabilities of PHOENIX and to cover various variations of the equations implemented as well as a number of different variants, types, and possibilities of post-processing that can be performed. Applications include extensions of our previous research [36,37,38,39,40] covering the fields of topology, non-Hermitian physics, nonlinear physics, and quantum-state tomography based on Monte Carlo simulations with quantum noise. This relatively broad spectrum of examples is intended to help the easy and widespread use of PHOENIX and its adaptation to other interesting scenarios. ...
June 2022
ACS Photonics
... Surface charge transfer-based doping [11], substitutional doping [12], interstitial doping [13], and vacancy-based doping [14] are the main post-growth doping mechanisms for 2D-TMDs [15]. Based on these mechanisms, there are several reported doping techniques such as chemical treatment [13], ion implantation [16], plasma doping [17], thermal annealing [18], electron beam irradiation [19], and ultraviolet-ozone (UV-O3) treatment [20], which aim to achieve n-and/or p-type doping. Due to the high sensitivity of 2D materials' properties, the main challenge in post-growth doping is to maintain their superb optoelectrical properties for device applications, while controlling the doping concentration with consistency. ...
October 2020
... Thus, polariton condensation is necessarily accompanied by the formation of an incoherent uncondensed excitonic reservoir [8]. Such a reservoir can also manifest itself indirectly in experiments via its repulsive interactions with polaritons [19][20][21][22], allowing the creation of on-demand trapping potentials by spatially selective laser excitation [23][24][25][26][27]. ...
June 2020
... A polariton dyad represents a pair of polariton condensates excited by localized optical beams in a plane of a microcavity, separated by a distance d from each other, see Fig. 1c-e. Excitation is performed in the nonresonant regime, where the energy of an excitation beam is considerably (tens of meV) higher than the polariton energy 41,42 . Such a pump creates a reservoir of incoherent high-energy excitons (see Fig. 1c), which in turn feeds the polariton condensate. ...
April 2020
ACS Photonics