arXiv subjects

Da-Wei Wang

Publications and source records attributed to Da-Wei Wang.

At least 37 records · Page 2Linked to original sources

arXiv2024

Testing the unified bounds of quantum speed limit

Quantum speed limits (QSLs) impose fundamental constraints on the evolution speed of quantum systems. Traditionally, the Mandelstam-Tamm (MT) and Margolus-Levitin (ML) bounds have been widely employed, relying on the standard deviation and mean of energy distribution to define the QSLs. However, these universal bounds only offer loose restrictions on the quantum evolution. Here we introduce the generalized ML bounds, which prove to be more stringent in constraining dynamic evolution, by utilizing moments of energy spectra of arbitrary orders, even noninteger orders. To validate our findings, we conduct experiments in a superconducting circuit, where we have the capability to prepare a wide range of quantum photonic states and rigorously test these bounds by measuring the evolution of the system and its photon statistics using quantum state tomography. While, in general, the MT bound is effective for short-time evolution, we identify specific parameter regimes where either the MT or the generalized ML bounds suffice to constrain the entire evolution. Our findings not only establish new criteria for estimating QSLs but also substantially enhance our comprehension of the dynamic evolution of quantum systems.

quant-ph↗

arXiv2024

Realization of all-band-flat photonic lattices

Flatbands play an important role in correlated quantum matter and have novel applications in photonic lattices. Synthetic magnetic fields and destructive interference in lattices are traditionally used to obtain flatbands. However, such methods can only obtain a few flatbands with most bands remaining dispersive. Here we realize all-band-flat photonic lattices of an arbitrary size by precisely controlling the coupling strengths between lattice sites to mimic those in Fock-state lattices. This allows us to go beyond the perturbative regime of strain engineering and group all eigenmodes in flatbands, which simultaneously achieves high band flatness and large usable bandwidth. We map out the distribution of each flatband in the lattices and selectively excite the eigenmodes with different chiralities. Our method paves a new way in controlling band structure and topology of photonic lattices.

physics.optics↗

arXiv2023

Interaction between giant atoms in a one-dimensional topological waveguide

In this paper, we consider giant atoms coupled to a one-dimensional topological waveguide reservoir. We studied the following two cases. In the bandgap regime, where the giant-atom frequency lies outside the band, we study the generation and distribution of giant atom-photon bound states and the difference between the topological waveguide in topological and trivial phases. When the strengths of the giant atoms coupled to the two sub-lattice points are equal, the photons distribution is symmetrical and the chiral photon distribution is exhibited when the coupling is different. The coherent interactions between giant atoms are induced by virtual photons, or can be understood as an overlap of photon bound-state wave functions, and decay exponentially with increasing distance between the giant atoms. We also find that the coherent interactions induced by the topological phase are larger than those induced by the trivial phase for the same bandgap width. In the band regime, the giant-atom frequency lies in the band, under the Born-Markov approximation, we obtained effective coherence and correlated dissipative interactions between the giant atoms mediated by topological waveguide reservoirs, which depend on the giant-atom coupling nodes. We analyze the effect of the form of the giant-atom coupling point on the decay, and on the associated dissipation. The results show that we can design the coupling form as well as the frequency of the giant atoms to achieve zero decay and correlation dissipation and non-zero coherent interactions. Finally we used this scheme to realize the excitation transfer of giant atoms. Our work will promote the study of topological matter coupled to giant atoms.

quant-ph↗

arXiv2023

Realizing the controllable excitation transfer based on the atom coupling the finite-size Su-Schrieffer-Heeger model

In this paper, we study the interaction between atom and the finite-size Su-Schrieffer-Heeger (SSH) model. We find that when the finite SSH model in the trivial phase, it can be viewed as the atom coupling with the waveguide with the finite bandwidths and non-linear dispersion relation. However, for the SSH model in the topological phase, when we consider the frequency of the atom is resonant with the edge mode of the SSH model, we find that the atom state couples to the two edge states. In this case, we find that there exists a special channel that can be utilized to transfer the atomic excitation to the ends of the SSH model using adiabatic processes. When the atom couples to the different sub-lattice, the excitation of the atom can be transferred to the leftmost or rightmost end of the chain, which provides the potential application toward quantum information processing. Furthermore, The excitation transfer of excited states of atoms to the ends of the chain can also be realized without the adiabatic process. Our work provides a pathway for realizing controllable quantum information transfer based on the atom couples topological matter.

quant-ph↗

arXiv2023

Programmable Photonic Simulator for Spin Glass Models

Spin glasses featured by frustrated interactions and metastable states have important applications in chemistry, material sciences and artificial neural networks. However, the solution of the spin glass models is hindered by the computational complexity that exponentially increases with the sample size. Photonic Ising machines based on spatial light modulation can speed up the calculation by obtaining the Hamiltonian from the modulated light intensity. However, the large-scale generalization to various spin couplings and higher dimensions is still elusive. Here, we develop a Fourier-mask method to program the spin couplings in photonic Ising machines. We observe the phase transition of the two-dimensional Mattis model and the J$\mathrm{_1}$-J$\mathrm{_2}$ model and study the critical phenomena. We also demonstrate that the three-dimensional Ising model, which has not been analytically solved, can be effectively constructed and simulated in two-dimensional lattices with Fourier masks. Our strategy provides a flexible route to tuning couplings and dimensions of statistical spin models, and improves the applicability of optical simulation in neural networks and combinatorial optimization problems.

cond-mat.dis-nn↗

arXiv2023

Coherent control of a high-orbital hole in a semiconductor quantum dot

Coherently driven semiconductor quantum dots are one of the most promising platforms for non-classical light sources and quantum logic gates which form the foundation of photonic quantum technologies. However, to date, coherent manipulation of single charge carriers in quantum dots is limited mainly to their lowest orbital states. Ultrafast coherent control of high-orbital states is obstructed by the demand for tunable terahertz pulses. To break this constraint, we demonstrate an all-optical method to control high-orbital states of a hole via stimulated Auger process. The coherent nature of the Auger process is proved by Rabi oscillation and Ramsey interference. Harnessing this coherence further enables the investigation of single-hole relaxation mechanism. A hole relaxation time of 161 ps is observed and attributed to the phonon bottleneck effect. Our work opens new possibilities for understanding the fundamental properties of high-orbital states in quantum emitters and developing new types of orbital-based quantum photonic devices.

quant-ph↗

arXiv2023

Observation of non-Hermitian antichiral edge currents

Non-Hermitian topological photonics is of great interest in bridging topological matter with gain/dissipation engineering in optics. A key problem in this direction is the interplay between the effective gauge potential and the non-Hermiticity. Here we tackle this problem in a synthetic non-Hermitian Hall ladder and experimentally observe antichiral edge currents (ACECs) of photons, by tuning the locally uniform effective magnetic flux and the on-site gain/loss. Such ACECs provide a topological method to probe the signatures of the non-Hermitian skin effect (NHSE) from steady-state bulk dynamics. The universality of this method is verified by its generalization to three dimensions. This study paves a way to investigate exotic non-Hermitian topological physics and has potential applications in topological photonics engineering.

physics.optics↗

arXiv2023

Extreme subradiance from two-band Bloch oscillations in atomic arrays

Atomic arrays provide an important quantum optical platform with photon-mediated dipoledipole interactions, which can be engineered to realize key applications in quantum information processing. A major obstacle for such application is the fast decay of the excited states. By controlling two-band Bloch oscillations in an atomic array under external magnetic field, here we show that exotic subradiance can be realized and maintained at a time scale upto 12 orders of magnitude larger than the spontaneous decay time in atomic arrays with the finite size. The key finding is to show a way for preventing the wavepacket of excited states scattering into the dissipative zone inside the free space light cone, which therefore leads to the excitation staying at a subradiant state for extremely long decay time. We show that such operation can be achieved by introducing a spatially linear potential from external magnetic field in atomic arrays and then manipulating interconnected two-band Bloch oscillations along opposite directions. Our results also point out the possibility of controllable switching between superradiant and subradiant states, which leads to potential applications in quantum storage.

quant-ph↗

arXiv2023

Quantum Induced Coherence Light Detection and Ranging

Quantum illumination has been proposed and demonstrated to improve the signal-to-noise ratio (SNR) in light detection and ranging (LiDAR). When relying on coincidence detection, such a quantum LiDAR is limited by the response time of the detector and suffers from jamming noise. Inspired by the Zou-Wang-Mandel experiment, we design, construct and validate a quantum induced coherence (QuIC) LiDAR which is inherently immune to ambient and jamming noises. In traditional LiDAR the direct detection of the reflected probe photons suffers from deteriorating SNR for increasing background noise. In QuIC LiDAR we circumvent this obstacle by only detecting the entangled reference photons, whose single-photon interference fringes are used to obtain the distance of the object, while the reflected probe photons are used to erase path information of the reference photons. In consequence, the noise accompanying the reflected probe light has no effect on the detected signal. We demonstrate such noise resilience with both LED and laser light to mimic the background noise and jamming attack. The proposed method paves a new way of battling noise in precise quantum electromagnetic sensing and ranging.

quant-ph↗

arXiv2022

Floquet superradiance lattices in thermal atoms

Floquet modulation has been widely used in optical lattices for coherent control of quantum gases, in particular for synthesizing artificial gauge fields and simulating topological matters. However, such modulation induces heating which can overwhelm the signal of quantum dynamics in ultracold atoms. Here we report that the thermal motion, instead of being a noise source, provides a new control knob in Floquet-modulated superradiance lattices, which are momentum-space tight-binding lattices of collectively excited states of atoms. The Doppler shifts combined with Floquet modulation provide effective forces along arbitrary directions in a lattice in frequency and momentum dimensions. Dynamic localization, dynamic delocalization and chiral edge currents can be simultaneously observed from a single transport spectrum of superradiance lattices in thermal atoms. Our work paves a way for simulating Floquet topological matters in room-temperature atoms and facilitates their applications in photonic devices.

cond-mat.quant-gas↗

arXiv2022

Measuring Zak phase in room-temperature atoms

Cold atoms provide a flexible platform for synthesizing and characterizing topolog-ical matter, where geometric phases play a central role. However, cold atoms are intrinsically prone to thermal noise, which can overwhelm the topological response and hamper promised applications. On the other hand, geometric phases also de-termine the energy spectra of particles subjected to a static force, based on the po-larization relation between Wannier-Stark ladders and geometric Zak phases. By exploiting this relation, we develop a method to extract geometric phases from en-ergy spectra of room-temperature superradiance lattices, which are momentum-space lattices of timed Dicke states. In such momentum-space lattices the thermal motion of atoms, instead of being a source of noise, provides effective forces which lead to spectroscopic signatures of the Zak phases. We measure Zak phases direct-ly from the anti-crossings between Wannier-Stark ladders in the Doppler-broadened absorption spectra of superradiance lattices. Our approach paves the way of measuring topological invariants and developing their applications in room-temperature atoms.

cond-mat.quant-gas↗

arXiv2022

Coherent control of quantum topological states of light in Fock-state lattices

Topological photonics provides a novel platform to explore topological physics beyond traditional electronic materials and stimulates promising applications in topologically protected light transport and lasers. Classical degrees of freedom such as polarizations and wavevectors are routinely used to synthesize topological light modes. Beyond the classical regime, inherent quantum nature of light gives birth to a wealth of fundamentally distinct topological states, which offer topological protection in quantum information processing. Here we implement such experiments on topological states of quantized light in a superconducting circuit, on which three resonators are tunably coupled to a gmon qubit. We construct one and two-dimensional Fock-state lattices where topological transport of zero-energy states, strain induced pseudo-Landau levels, valley Hall effect and Haldane chiral edge currents are demonstrated. Our study extends the topological states of light to the quantum regime, bridges topological phases of condensed matter physics with circuit quantum electrodynamics, and offers a new freedom in controlling the quantum states of multiple resonators.

quant-ph↗

arXiv2021

Synthesizing five-body interaction in a superconducting quantum circuit

Synthesizing many-body interaction Hamiltonian is a central task in quantum simulation. However, it is challenging to synthesize interactions including more than two spins. Borrowing tools from quantum optics, we synthesize five-body spin-exchange interaction in a superconducting quantum circuit by simultaneously exciting four independent qubits with time-energy correlated photon quadruples generated from a qudit. During the dynamic evolution of the five-body interaction, a Greenberger-Horne-Zeilinger state is generated in a single step with fidelity estimated to be $0.685$. We compare the influence of noise on the three-, four- and five-body interaction as a step toward answering the question on the quantum origin of chiral molecules. We also demonstrate a many-body Mach-Zehnder interferometer which potentially has a Heisenberg-limit sensitivity. This study paves a way for quantum simulation involving many-body interactions and high excited states of quantum circuits.

quant-ph↗

arXiv2021

Recognizing three-dimensional phase images with deep learning

Optical phase contains key information for biomedical and astronomical imaging. However, it is often obscured by layers of heterogeneous and scattering media, which render optical phase imaging at different depths an utmost challenge. Limited by the memory effect, current methods for phase imaging in strong scattering media are inapplicable to retrieving phases at different depths. To address this challenge, we developed a speckle three-dimensional reconstruction network (STRN) to recognize phase objects behind scattering media, which circumvents the limitations of memory effect. From the single-shot, reference-free and scanning-free speckle pattern input, STRN distinguishes depth-resolving quantitative phase information with high fidelity. Our results promise broad applications in biomedical tomography and endoscopy.

physics.optics↗

arXiv2021

Simulating graphene dynamics in one-dimensional modulated ring array with synthetic dimension

A dynamically-modulated ring system with frequency as a synthetic dimension has been shown to be a powerful platform to do quantum simulation and explore novel optical phenomena. Here we propose synthetic honeycomb lattice in a one-dimensional ring array under dynamic modulations, with the extra dimension being the frequency of light. Such system is highly re-configurable with modulation. Various physical phenomena associated with graphene including Klein tunneling, valley-dependent edge states, effective magnetic field, as well as valley-dependent Lorentz force can be simulated in this lattice, which exhibits important potentials for manipulating photons in different ways. Our work unveils a new platform for constructing the honeycomb lattice in a synthetic space, which holds complex functionalities and could be important for optical signal processing as well as quantum computing.

physics.optics↗

arXiv2021

Arbitrary synthetic dimensions via multi-boson dynamics on a one-dimensional lattice

The synthetic dimension, a research topic of both fundamental significance and practical applications, is attracting increasing attention in recent years. In this paper, we propose a theoretical framework to construct arbitrary synthetic dimensions, or N-boson synthetic lattices, using multiple bosons on one-dimensional lattices. We show that a one-dimensional lattice hosting N indistinguishable bosons can be mapped to a single boson on a N-dimensional lattice with high symmetry. Band structure analyses on this N-dimensional lattice can then be mathematically performed to predict the existence of exotic eigenstates and the motion of N-boson wavepackets. As illustrative examples, we demonstrate the edge states in two-boson Su-Schrieffer-Heeger synthetic lattices without interactions, interface states in two-boson Su-Schrieffer-Heeger synthetic lattices with interactions, and weakly-bound triplon states in three-boson tight-binding synthetic lattices with interactions. The interface states and weakly-bound triplon states have not been thoroughly understood in previous literatures. Our proposed theoretical framework hence provides a novel perspective to explore the multi-boson dynamics on lattices with boson-boson interactions, and opens up a future avenue in the fields of multi-boson manipulation in quantum engineering.

quant-ph↗

arXiv2021

Unification of valley and anomalous Hall effects in a strained lattice

Two dimensional lattices are an important stage for studying many aspects of quantum physics, in particular the topological phases. The valley Hall and anomalous Hall effects are two representative topological phenomena. Here we show that they can be unified in a strained honeycomb lattice, where the hopping strengths between neighboring sites are designed by mimicking those between the Fock states in a three-mode Jaynes-Cummings model. Such a strain induces an effective magnetic field which results in quantized Landau levels. The eigenstates in the zeroth Landau level can be represented by the eigenstates of a large pseudo-spin. We find that the valley Hall current and the chiral edge current in the Haldane model correspond to the spin precession around different axes. Our study sheds light on connection between seemingly unrelated topological phases in condensed matter physics.

cond-mat.mes-hall↗

arXiv2020

Second Harmonic Imaging Enhanced by Deep Learning Decipher

Wavefront sensing and reconstruction are widely used for adaptive optics, aberration correction, and high-resolution optical phase imaging. Traditionally, interference and/or microlens arrays are used to convert the optical phase into intensity variation. Direct imaging of distorted wavefront usually results in complicated phase retrieval with low contrast and low sensitivity. Here, a novel approach has been developed and experimentally demonstrated based on the phase-sensitive information encoded into second harmonic signals, which are intrinsically sensitive to wavefront modulations. By designing and implementing a deep neural network, we demonstrate the second harmonic imaging enhanced by deep learning decipher (SHIELD) for efficient and resilient phase retrieval. Inheriting the advantages of two-photon microscopy, SHIELD demonstrates single-shot, reference-free, and video-rate phase imaging with sensitivity better than λ/100 and high robustness against noises, facilitating numerous applications from biological imaging to wavefront sensing.

physics.optics↗