Direct observation of exceptional points in coupled photonic-crystal lasers with asymmetric optical gains

Kim, Kyoung-Ho; Hwang, Miriam; Kim, Ha Reem; Choi, Jae Hyuck; No, You Shin; Park, Hong Gyu

doi:10.1038/ncomms13893

Cited by 99 publications

(63 citation statements)

References 44 publications

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“…Tunable dissipative environments for circuit quantum electrodynamics (cQED) are pursued intensively in experiments due to the unique opportunities to study non-Hermitian physics 1,2 , such as phase transitions related to parity-time symmetry 3 , decoherence and quantum noise 4 . Interesting effects can be observed in experiments on exceptional points [5][6][7] , which also gives possibilities to use such systems as models in nonlinear photonics, for example, for metamaterials 8 and for photonic crystals 9 .…”

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confidence: 99%

Fast control of dissipation in a superconducting resonator

Sevriuk

Tan

Hyyppä

et al. 2019

Applied Physics Letters

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We report on fast tunability of an electromagnetic environment coupled to a superconducting coplanar waveguide resonator. Namely, we utilize a recently-developed quantum-circuit refrigerator (QCR) to experimentally demonstrate a dynamic tunability in the total damping rate of the resonator up to almost two orders of magnitude. Based on the theory it corresponds to a change in the internal damping rate by nearly four orders of magnitude. The control of the QCR is fully electrical, with the shortest implemented operation times in the range of 10 ns. This experiment constitutes a fast active reset of a superconducting quantum circuit. In the future, a similar scheme can potentially be used to initialize superconducting quantum bits.Tunable dissipative environments for circuit quantum electrodynamics (cQED) are pursued intensively in experiments due to the unique opportunities to study non-Hermitian physics 1,2 , such as phase transitions related to parity-time symmetry 3 , decoherence and quantum noise 4 . Interesting effects can be observed in experiments on exceptional points 5-7 , which also gives possibilities to use such systems as models in nonlinear photonics, for example, for metamaterials 8 and for photonic crystals 9 .From the practical point of view, tunable environments are utilized to protect and process quantum information 10-12 and to implement qubit reset 13,14 . The latter application calls for fast tunability of the environment due to the aim to increase the rate of the operations on a quantum computer. Recent advances in the field of cQED for quantum information processing 14-17 render this topic highly interesting.There are different ways for resetting superconducting qubits. Firstly, one may tune the qubit frequency to reduce its life time 18 . The disadvantages of this method include the broad frequency band reserved by the qubit and the required fast frequency sweep which may lead to an increased amount of initialization error 19 . Conventionally, it is beneficial to maintain the qubits at the optimal parameter points during all operations. Secondly, it is possible to use microwave pulses to actively drive the qubit to the ground state 20-23 . Such methods are popular because no additional components or new control steps are needed. However, to achieve high fidelity one usually needs to increase the reset time to the microsecond range. Thirdly, one can engineer a tunable environment for the qubits 13,24-26 . This approach demand changes in the chip design, but may lead to high fidelity for a fast reset without compromises on the other properties.Here, we focus on a single-parameter-controlled tunable environment implemented by a quantum-circuit refrigerator (QCR) 5,27-31 . The refrigerator is based on photonassisted electron tunneling through two identical normalmetal-insulator-superconductor junctions (NIS). It has been used to cool down a photon mode of the resonator 27 , and to observe a Lamb shift in a cQED system 31 . Furthermore, QCR can be used as a cryogenic photon source 29 , which ma...

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mentioning

confidence: 99%

Fast control of dissipation in a superconducting resonator

Sevriuk

Tan

Hyyppä

et al. 2019

Applied Physics Letters

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“…In the presence of balanced gain and loss, the rhombic ring structure is under reflection PT-symmetry, which induces asymmetric reflection and reciprocal transmission. The optical gain and loss in the coupledresonator optical systems can be experimentally realized using InGaAsP quantum wells and chrome or graphene layers, respectively, on top of the resonator [63][64][65][66][67].…”

Section: Unidirectional Reflectionless Propagation In Pt-symmetric Symentioning

confidence: 99%

Unidirectional reflectionless light propagation at exceptional points

et al. 2017

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Abstract:In this paper, we provide a comprehensive review of unidirectional reflectionless light propagation in photonic devices at exceptional points (EPs). EPs, which are branch point singularities of the spectrum, associated with the coalescence of both eigenvalues and corresponding eigenstates, lead to interesting phenomena, such as level repulsion and crossing, bifurcation, chaos, and phase transitions in open quantum systems described by non-Hermitian Hamiltonians. Recently, it was shown that judiciously designed photonic synthetic matters could mimic the complex non-Hermitian Hamiltonians in quantum mechanics and realize unidirectional reflection at optical EPs. Unidirectional reflectionlessness is of great interest for optical invisibility. Achieving unidirectional reflectionless light propagation could also be potentially important for developing optical devices, such as optical network analyzers. Here, we discuss unidirectional reflectionlessness at EPs in both parity-time (PT)-symmetric and non-PT-symmetric optical systems. We also provide an outlook on possible future directions in this field.

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“…It is this simplicity of the kagome-based design in terms of fabrication and its unidirectional edge mode transport which makes it an ideal candidate for practical applications at nearinfrared and visible wavelengths. Indeed, we present and model the predicted behaviour for an on-chip platform that can be readily fabricated with state-of-the-art semiconductor growth techniques [15].The kagome lattice, named after a traditional Japanese basketweave pattern [14], has lattice sites at the midpoints of the edges in the regular hexagonal wallpaper tiling {6, 3}, as illustrated in Fig. 1(a).…”

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confidence: 99%

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confidence: 99%

Gapless unidirectional photonic transport using all-dielectric kagome lattices

Wong

Saba

Hess

et al. 2020

Phys. Rev. Research

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Photonic topological insulators are a promising photonic platform due to the possibility of unidirectional edge states with insensitivity to bending, fabrication imperfections or environmental fluctuation. Here we demonstrate highly efficient unidirectional photonic edge mode propagation facilitated by the optical quantum valley Hall effect. With an all-dielectric kagome lattice design, we demonstrate broadband suppressed reflection in the presence of sharp corners and further show negligible vertical losses in a semiconductor-based device at telecommunication wavelengths.When propagating in a (structured) material or waveguide, not all of the light travels in this initial direction but parts of it experience back-reflection due to bending, fabrication defects or environmental variations. For most applications back-propagation should be avoided and it is thus not surprising that the unique properties of photonic topological insulators (PTIs) [1] have attracted widespread attention due to their promise to prohibit back-reflections. The basis of such back-scattering-free one-way waveguides lies at the interface of two topologically inequivalent photonic crystals (PhCs) which exhibit topological edge modes that -guaranteed by the bulk-boundary correspondence [2] -propagate only in one direction and are at the same time robust against perturbations. Not surprisingly, a plethora of possible topologically non-trivial photonic designs has been put forward, involving non-reciprocal systems [3], complex metamaterials [4], the Floquet topological insulator principle [5], and an artificial magnetic gauge [6,7]. However, the aforementioned PTIs need strong magnetic fields, are complicated to fabricate, and/or are difficult if not impossible to scale to optical frequencies.As an alternative, a deformed honeycomb-based topological PhC [8] which emulates the quantum spin Hall effect (QSHE) [9] has recently gained interest, not least due to its simple fabrication as compared to other PTIs. Nevertheless, while 2D hexagonal symmetries (such as the honeycomb-based topological PhC) generally lead to Dirac cones at the K and K points of the Brillouin zone (BZ), and with a geometrical perturbation it is possible to lift the point-like degeneracies in order to obtain a nontrivial topological and complete photonic band gap [10] (which leads to topological protection defined within the parameter space of a certain type of a deterministic geometrical perturbation that differs from the traditional Hatsugai sense [2]), there is an inherent problem. The pseudo-time-reversal anti-unitary operator T 2 = − 1, introduced to have well-defined orthogonal spin up/down channels, is constructed on the basis of the six-fold rota- * Email: wongs16@cardiff.ac.uk † Email: ohs2@cardiff.ac.uk tion (C 6 ) operator of the crystal. However, the C 6 symmetry of the crystal is broken in any finite, truncated, configuration and the spin up and spin down channels couple to each other. Consequently, while edge modes are guaranteed at the interface between the two ...

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Direct observation of exceptional points in coupled photonic-crystal lasers with asymmetric optical gains

Cited by 99 publications

References 44 publications

Fast control of dissipation in a superconducting resonator

Fast control of dissipation in a superconducting resonator

Unidirectional reflectionless light propagation at exceptional points

Gapless unidirectional photonic transport using all-dielectric kagome lattices

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