The efficient preparation of collective eigenstates of subwavelength-spaced optical dipoles is a prerequisite for observing their signature radiative properties and for their applications in quantum information processing. We theoretically investigate the deterministic preparation of super- and subradiant states of two dipole-coupled two-level quantum emitters at deep-subwavelength separation using the Swing-UP of quantum EmitteR population (SUPER) excitation scheme. Utilizing suitable pulse parameters for two red-detuned, time-overlapping Gaussian pulses, the SUPER scheme enables close-to-unity population inversion in the targeted collective eigenstates. Furthermore, a tunable optical phase in the SUPER scheme enables the simultaneous inversions in both pure super- and subradiant states with finite populations, thereby resulting in the preparation of hybrid collective states. These results are possible to realize with or without an optical cavity. Our approach to populating the collective eigenstates in a cavity environment paves the way for the efficient preparation of these states in the presence of environmental decoherence. Our scheme enables single-photon generation, which is measured using the second-order correlation function. We also discuss in detail possible experimental realizations, in particular using solid-state emitters and molecules.
The efficient preparation of collective eigenstates of subwavelength-spaced optical dipoles is a prerequisite for observing their signature radiative properties and for their applications in quantum information processing. We theoretically investigate the deterministic preparation of super- and subradiant states of two dipole-coupled two-level quantum emitters at deep-subwavelength separation using the Swing-UP of quantum EmitteR population (SUPER) excitation scheme. Utilizing suitable pulse parameters for two red-detuned, time-overlapping Gaussian pulses, the SUPER scheme enables close-to-unity population inversion in the targeted collective eigenstates. Furthermore, a tunable optical phase in the SUPER scheme enables the simultaneous inversions in both pure super- and subradiant states with finite populations, thereby resulting in the preparation of hybrid collective states. These results are possible to realize with or without an optical cavity. Our approach to populating the collective eigenstates in a cavity environment paves the way for the efficient preparation of these states in the presence of environmental decoherence. Our scheme enables single-photon generation, which is measured using the second-order correlation function. We also discuss in detail possible experimental realizations, in particular using solid-state emitters and molecules.
The Swing-UP of quantum EmitteR population (SUPER) scheme has recently been proposed as a deterministic method for the preparation of collective radiative states in two strongly dipole-coupled quantum emitters (Phys. Rev. Res. \textbf{8}, 013179 (2026)). Here, we apply this approach to an equilateral subwavelength triangular trimer of dipole-coupled two-level quantum emitters (QEs), loosely inspired by biological light-harvesting ring geometries, and demonstrate that tailored, time-overlapping, red-detuned ultrashort SUPER pulses can selectively prepare collective states in a C3-symmetric system, including energetically degenerate eigenstates that are resolved through site-dependent optical phases. We find that both the state selectivity and the preparation efficiency depend strongly on the inter-emitter spacing. In particular, at deep-subwavelength separations, the symmetric collective state can be deterministically prepared with near-unity efficiency (approximately 94%), whereas the inversion efficiency and state selectivity are significantly lower at larger inter-emitter separations. Furthermore, this state preparation technique inherits a certain degree of robustness against reasonable static position imperfections and on-site frequency inhomogeneities of the individual QEs. Our results demonstrate that deep-subwavelength triangular trimers and, more broadly, highly compact ring geometries are excellent candidates for the deterministic preparation of collective radiative states via SUPER excitation. These predictions could be realized with solid-state emitters and molecules. Our findings offer a route toward the direct probing of the `pure' electromagnetic layer of interaction in biological and bio-inspired synthetic nanophotonic ring configurations, with possible relevance in photonics, quantum information processing, and metrology.
In the SUPER scheme (Swing-UP of the quantum EmitteR population), excitation of a quantum emitter is achieved with two off-resonant, red-detuned laser pulses. This allows the generation of high-quality single photons without the need of complex laser stray light suppression or careful spectral filtering. In the present work, we extend this promising method to quantum emitters, specifically semiconductor quantum dots, inside a resonant optical cavity. A significant advantage of the SUPER scheme is identified in that it eliminates re-excitation of the quantum emitter by suppressing photon emission during the excitation cycle. This, in turn, leads to almost ideal single-photon purity, overcoming a major factor typically limiting the quality of photons generated with quantum emitters in high-quality cavities. We further find that for cavity-mediated biexciton emission of degenerate photon pairs, the SUPER scheme leads to near-perfect biexciton initialization with very high values of polarization entanglement of emitted photon pairs. Published by the American Physical Society 2024
Coherent control of quantum emitters is essential for scalable quantum photonic technologies. The recently proposed swing up of the quantum emitter population (SUPER) scheme allows efficient and coherent state preparation via off-resonant, red-detuned laser pulses, simplifying laser suppression and enhancing photon collection. We present a systematic study of SUPER excitation applied to a single GaAs quantum dot in a low- Q micropillar cavity. We first identify the optimal excitation conditions for SUPER, and then compare the key figures of merit against the well-established two-photon excitation (TPE). Despite requiring higher excitation powers, SUPER achieves near-unity population inversion of the exciton state ( ∼ 95 % ) and high single-photon purity ( g ( 2 ) = 0.03 ) comparable to that under TPE, while also exhibiting a shortened decay time ( ∼ 200 ps) reducing the time jitter in the exciton population. A polarization-resolved analysis reveals that when both excitation and collection are aligned with one of the exciton dipoles, SUPER results in highly polarized single-photon emission, exceeding the resonant TPE saturation by a factor of 1.45. Under optimized excitation conditions, we also observe biexciton preparation via a distinct SUPER resonance, constituting an experimental demonstration of biexciton preparation using SUPER. These findings are in good agreement with a proposed four-level theoretical model that incorporates the biexciton state. Furthermore, we report that, strikingly, a slight misalignment of laser polarization induces an additional SUPER resonance that selectively populates the orthogonal exciton dipole, without altering the nominal excitation polarization. This unexpected behavior reveals a new degree of freedom for coherent state preparation. Our findings establish the SUPER scheme as a versatile tool for state-selective exciton and biexciton control, with strong potential for quantum photonic applications.
Single or entangled photon states are vital for quantum communication. They can be generated on-demand by solid-state quantum emitters. Achieving high-fidelity photons depends on the excitation process. In addition to more established schemes, we present a radically different excitation scheme using two red-detuned laser pulses through the swing-up (SUPER) effect. The SUPER scheme is compared to other schemes like Rabi rotations, phonon-assisted preparation and adiabatic rapid passage. Experimental demonstrations of the different schemes are pointed out. With this, we highlight advancements in photon generation from solid-state quantum emitters.
The quest for the perfect single-photon source includes finding the optimal protocol for exciting the quantum emitter. Coherent optical excitation was, up until now, achieved by tuning the laser pulses to the transition frequency of the emitter, either directly or in average. Recently, it was theoretically discovered that an excitation with two red-detuned pulses is also possible where neither of which would yield a significant upper-level population individually. We show that the so-called swing-up of quantum emitter population (SUPER) scheme can be implemented experimentally with similar properties to existing schemes by precise amplitude shaping of a broadband pulse. Because of its truly off-resonant nature, this scheme has the prospect of powering high-purity photon sources with superior photon count rate.
The Swing-UP of the quantum EmitteR population (SUPER) two-color pulsed excitation scheme allows for robust and close to 100\% excitation of a two-level quantum emitter using only red detuned light. We analyze the underlying counterintuitive dynamics using a full quantum input-output description of the in- and outgoing light pulses for the case of two coherent free-space input pulses at realistic photon numbers. At the microscopic level, the SUPER mechanism exhibits its nonlinear three-photon Raman-type character, leading to a net photon-number change of −2 in one mode and +1 in the other, as was first guessed from cavity-enhanced model descriptions at low photon numbers. We confirm that in free space, a sufficiently high pulse photon number, much larger than one, is required to achieve high-fidelity inversion. To treat the large coherent-state amplitudes (photon numbers) relevant for SUPER, we extend the quantum input-output formalism to include a cumulant expansion approach. With an interaction-picture formulation, the few exchanged photons that govern the nontrivial dynamics enable direct full-quantum calculations in truncated Hilbert spaces, including treatments in a displacement frame and for initial Fock-state pulses.