All-optical Setup Research Articles

Experimental Test of High-Dimensional Quantum Contextuality Based on Contextuality Concentration.

Contextuality is a distinctive feature of quantum theory and a fundamental resource for quantum computation. However, existing examples of contextuality in high-dimensional systems lack the necessary robustness required in experiments. Here, we address this problem by identifying a family of noncontextuality inequalities whose maximum quantum violation grows with the dimension of the system. At first glance, this contextuality is the single-system version of multipartite Bell nonlocality taken to an extreme form. What is interesting is that the single-system version achieves the same degree of contextuality but uses a Hilbert space of lower dimension. That is, contextuality "concentrates" as the degree of contextuality per dimension increases. We show the practicality of this result by presenting an experimental test of contextuality in a seven-dimensional system. By simulating sequences of quantum ideal measurements with destructive measurements and repreparation in an all-optical setup, we report a violation of 68.7 standard deviations of the simplest case of the noncontextuality inequalities identified. Our results advance the investigation of high-dimensional contextuality, its connection to the Clifford algebra, and its role in quantum computation.

Proposal for a long-distance nonlocality test with entanglement swapping and displacement-based measurements

We analyze an all-optical setup which enables Bell-inequality violation over long distances by exploiting probabilistic entanglement swapping. The setup involves only two-mode squeezers, displacements, beamsplitters, and on-off detectors. We describe how events must be arranged to close both the detection and locality loopholes. We analyze a scenario with dichotomic inputs and outputs, and check the robustness of the Bell inequality violation for up to six parties, with respect to phase, amplitude, and dark count noise, as well as loss.

Measuring Near-Field Radiative Heat Transfer in a Graphene- SiC Heterostructure

Near-field radiative heat transfer between closely placed objects may exceed the far-field black-body radiation limit by orders of magnitude, especially between polaritonic materials. Great efforts have been made to experimentally measure this fundamental effect in various systems. In this work, we manage to experimentally characterize the near-field thermal emission between less explored plasmon-phonon hybrid material systems made of a graphene-$\mathrm{Si}\mathrm{C}$ heterostructure. The experiment is carried out using a custom-designed all-optical measurement setup. A heat flux enhancement factor of 26 over the black-body radiation limit is obtained at a 150-nm vacuum gap. Three fundamental modes, i.e., surface plasmon and phonon polaritons with frustrated modes, are identified to contribute the near-field heat flux in this hybrid system. The measured results are well reproduced from the analytical calculations, indicating the robustness of the measurement. Deeper experimental explorations for near-field heat transfer between more complicated material systems could be encouraged in the future.

Towards single atom computing via high harmonic generation

The development of alternative platforms for computing has been a longstanding goal for physics, and represents a particularly pressing concern as conventional transistors approach the limit of miniaturization. A potential alternative paradigm is that of reservoir computing, which leverages unknown, but highly nonlinear transformations of input-data to perform computations. This has the advantage that many physical systems exhibit precisely the type of nonlinear input-output relationships necessary for them to function as reservoirs. Consequently, the quantum effects which obstruct the further development of silicon electronics become an advantage for a reservoir computer. Here we demonstrate that even the most basic constituents of matter–atoms–can act as a reservoir for computing where all input-output processing is optical, thanks to the phenomenon of High Harmonic Generation. A prototype single-atom computer for classification problems is proposed, where a classification model is mapped to an all-optical setup, with linear filters chosen to correspond to the trained model’s parameters. We numerically demonstrate that this ‘all-optical’ computer can successfully perform classification tasks, and does so with an accuracy that is strongly dependent on dynamical nonlinearities. This may pave the way for the development of petahertz information processing platforms.

Generation of bright collimated vortex γ -ray via laser driven cone-fan target

We use numerical simulations to demonstrate that a source of bright collimated vortex γ-ray with large orbital angular momentum and small divergence can be achieved by irradiating an intense circularly polarized laser on a cone-fan target. In the all-optical setup, electron beam of energy with hundreds of MeV and also vortex laser pulse are formed. A considerable fraction of angular momentum of laser is converted to electron beam and furthermore to final vortex γ-ray, which are roughly 27.8% and 3%, respectively. The conversion efficiency of energy from laser to them is around 41% and 3.8%. Moreover, comparative simulations for different inner sizes of the cone reveal that there exists an optimal size making the highest angular momentum of γ-ray photons. For simulations with different laser modes, the circularly polarized laser is more appropriate rather than the Laguerre–Gaussian one to generate vortex γ-ray.

All-optical nonlinear Breit-Wheeler pair production with γ -flash photons

High-power laser facilities give experimental access to fundamental strong-field quantum electrodynamics processes. A key effect to be explored is the nonlinear Breit-Wheeler process: the conversion of high-energy photons into electron-positron pairs through the interaction with a strong electromagnetic field. A major challenge to observing nonlinear Breit-Wheeler pair production experimentally is first having a suitable source of high-energy photons. In this paper we outline a simple all-optical setup which efficiently generates photons through the so-called $\ensuremath{\gamma}$-flash mechanism by irradiating a solid target with a high-power laser. We consider the collision of these photons with a secondary laser and systematically discuss the prospects for exploring the nonlinear Breit-Wheeler process at current and next-generation high-power laser facilities.

Renormalizing Antiferroelectric Nanostripes in β′-In2Se3 via Optomechanics

Antiferroelectric (AFE) materials have attracted a great deal of attention owing to their high energy conversion efficiency and good tunability. Recently, an exotic two-dimensional AFE material, a β'-In2Se3 monolayer that could host atomically thin AFE nanostripe domains, has been experimentally synthesized and theoretically examined. In this work, we apply first-principles calculations and theoretical estimations to predict that light irradiation can control the nanostripe width of such a system. We suggest that an intermediate near-infrared light (below the bandgap) could effectively harness the thermodynamic Gibbs free energy and thermodynamic stability, and the AFE nanostripe width will gradually decrease. We also propose to use linearly polarized light above the bandgap to generate an AFE nanostripe-specific photocurrent, providing an all-optical pump-probe setup for such AFE nanostripe width phase transitions.

Shaping the spin wave spectra of planar 1D magnonic crystals by the geometrical constraints

We present experimental and numerical studies demonstrating the influence of geometrical parameters on the fundamental spin-wave mode in planar 1D magnonic crystals. The investigated magnonic crystals consist of flat stripes separated by air gaps. The adjustment of geometrical parameters allows tailoring of the spin-wave frequencies. The width of stripes and the width of gaps between them affect spin-wave frequencies in two ways. First, directly by geometrical constraints confining the spin waves inside the stripes. Second, indirectly by spin-wave pinning, freeing the spin waves to a different extent on the edges of stripes. Experimentally, the fundamental spin-wave mode frequencies are measured using an all-optical pump-probe time-resolved magneto-optical Kerr-effect setup. Our studies address the problem of spin-wave confinement and spin-wave dipolar pinning in an array of coupled stripes. We show that the frequency of fundamental mode can be tuned to a large extent by adjusting the width of the stripes and the width of gaps between them.

High brilliance γ-ray generation from the laser interaction in a carbon plasma channel

The generation of collimated, high brilliance γ-ray beams from a structured plasma channel target is studied by means of 2D PIC simulations. Simulation results reveal an optimum laser pulse duration of 20 fs for generating photon beams of brilliances up to 1020 s−1mm−1mrad−2 (0.1 %BW)−1 with photon energies well above 200 MeV in the interaction of an ultra-intense laser (incident laser power PL ≥ 5 PW) with a high-Z carbon structured plasma target. These results are aimed at employing the upcoming laser facilities with multi-petawatt (PW) laser powers to study the laser-driven nonlinear quantum electrodynamics processes in an all-optical laboratory setup.

Optical tractor beam for a cluster of plasmonic and dielectric and chiral Mie objects

A light beam pushes any object towards the direction of its propagation as light or quantum of light, photon, carries momentum. However, a light beam can also pull a particle backward towards the source — regarded as an optical tractor beam. Despite a series of phenomenal works being done in the field of optical manipulation using optical tractor beams, optical setup that can enable the optical pulling of all objects (i.e., dielectric, plasmonic and chiral) is still extremely rare. This work stands as the very first proposal of a simple and generic all-optical setup, where attaining optical tractor beam effect over all objects within a cluster is facilitated. Such optical pulling effect is observed only over a dielectric substrate (but not over plasmonic substrate) when two simple plane waves superimpose appropriately maintaining certain conditions. The emergence of such counterintuitive force has been explained based on distinct physical phenomena. For instance, in case of the dielectric and chiral nanoparticles, origin of the pulling force has been explained based on the field induced multipole radiation; whereas, in case of the plasmonic scatterer, the pulling has been explained based on the reversal of induced current density within the object.

Multi-frame multi-exposure shock wave imaging and pressure measurements.

Shock wave visual detection was traditionally performed using streak cameras, limited to homogeneous shock wave emission, with the corresponding shock wave pressure measurements available at rather large distances or numerically estimated through equation of state for water. We demonstrate a multi-frame multi-exposure shock wave velocity measurement technique for all in-plane directions of propagation, based on custom-built illumination system allowing multiple illumination pulses within each frame at multi-MHz frame rates and at up to 200 MHz illumination pulse repetition frequency at sub-nanosecond pulse durations. The measurements are combined and verified using a fiber-optic probe hydrophone, providing independent shock wave pressure and time-of-flight measurements, creating a novel all-optical measurement setup. The measured pressures at distances around 100 µm from the plasma center exceed 500 MPa, while camera-based measurements at even shorter distances indicate pressures above 1 GPa.

Coherent energy fluctuation theorems: theory and experiment

Fluctuation theorems (FT) reveal crucial properties about the nature of non-equilibrium dynamics by constraining the statistical distribution of quantities such as heat, work and entropy production. Here, we report theoretical and experimental results regarding two FT for a new quantity, named coherent energy, which is an energy form directly associated with the coherences of a quantum state. The FT are verified using the two-point measurement protocol with an all-optical setup in which the system information is encoded in the polarization of one photon of a pair. From the outcomes of our experiment we directly assess the energy probability distributions. We also demonstrate an universal bound on the energy of thermal states under the action of unitary operations, which could be the first step to establish an arrow of time for reversible processes.

Optical demonstration of quantum fault-tolerant threshold

A major challenge in practical quantum computation is the ineludible errors caused by the interaction of quantum systems with their environment. Fault-tolerant schemes, in which logical qubits are encoded by several physical qubits, enable to the output of a higher probability of correct logical qubits under the presence of errors. However, strict requirements to encode qubits and operators render the implementation of a full fault-tolerant computation challenging even for the achievable noisy intermediate-scale quantum technology. Especially the threshold for fault-tolerant computation still lacks experimental verification. Here, based on an all-optical setup, we experimentally demonstrate the existence of the threshold for the fault-tolerant protocol. Four physical qubits are represented as the spatial modes of two entangled photons, which are used to encode two logical qubits. The experimental results clearly show that when the error rate is below the threshold, the probability of correct output in the circuit, formed with fault-tolerant gates, is higher than that in the corresponding non-encoded circuit. In contrast, when the error rate is above the threshold, no advantage is observed in the fault-tolerant implementation. The developed high-accuracy optical system may provide a reliable platform to investigate error propagation in more complex circuits with fault-tolerant gates.

Experimental Investigation of Quantum Uncertainty Relations With Classical Shadows

The quantum component in uncertainty relation can be naturally characterized by the quantum coherence of a quantum state, which is of paramount importance in quantum information science. Here, we experimentally investigate quantum uncertainty relations construed with relative entropy of coherence, l1 norm of coherence, and coherence of formation. Instead of quantum state tomographic technology, we employ the classical shadow algorithm for the detection of lower bounds in quantum uncertainty relations. With an all-optical setup, we prepare a family of quantum states whose purity can be fully controlled. We experimentally explore the tightness of various lower bounds in different reference bases on the prepared states. Our results indicate that the tightness of quantum coherence lower bounds depends on the reference bases and the purity of the quantum state.

Photo-magnetization in two-dimensional sliding ferroelectrics

Light–matter interaction is one of the key routes to understanding and manipulating geometric and electronic behaviors of materials, especially two-dimensional materials which are optically accessible owing to their high surface to volume ratio. In the current work, we focus on the recently discovered two-dimensional sliding ferroelectric materials, in which the out-of-plane electric polarization can be switched with a small horizontal translation in one layer. Combining symmetry analysis and first-principles calculations, we predict that light illumination could inject non-equilibrium magnetic moments into the sliding ferroelectrics. Such magnetic moment is composed of both spin and orbital degrees of freedom contributions. We use ZrI2, WTe2, and MoS2 bilayer ferroelectrics to illustrate our theory. Under intermediate light illumination, one can yield non-equilibrium magnetic moments on the order of 0.1–1 μB in these systems, which also depends on the polarization nature of incident light. Furthermore, we show that such photo-injected magnetism changes its sign when the sliding dipole moment switches. This photo-magnetization can be detected by magneto-optical methods (such as Kerr or Faraday effect), which serves as an indicator of sliding ferroelectricity. Hence, one can use an all-optical pump and probe setup to measure and detect the subtle sliding ferroelectric phase.

Gabor’s holography: seven decades influencing optics [Invited

Dennis Gabor's seminal idea of a simple all-optical setup aimed at reconstructing the object wavefront stored on a photographic plate gave birth a little over seven decades ago to the field of holography. In 1971 Gabor obtained the Nobel Prize in Physics for this invention. Still, the road in the early days after his two first papers on the subject was one full of obstacles, so his scientific and engineering contemporaries put his idea to rest for more than 10 years, until the invention of the laser. This fact made his holographic concept take off to new and unsuspected applications. This invited review paper is a homage to Dennis Gabor's 50th anniversary of his Nobel Prize accolade. For this purpose, the review departs from the typical common route, i.e., those written following a timeline fashion, and instead is written with the intent to cover only a few of the holography applications in optics while scanning the electromagnetic spectrum. In doing this, the authors are aware that other invited papers for this special issue will tackle other subjects not dealt with in this review non-timeline paper.

Experimental certification of the steering criterion based on the local uncertainty relation

Quantum nonlocality is a prominent discrepancy when we compare quantum physics with classical physics, and it manifests in different forms, one of which is quantum steering. Quantum steering refers to a correlation produced from a bipartite entangled state between the local measurement outcomes of one party and the postmeasurement states of the other. Combining with uncertainty relation, local measurements can be used to distinguish whether a quantum state is steerable. Thus, this method can be treated as an effective steering criterion. In this work, we certify this steering criterion based on the local uncertainty relation by an all-optical setup with a mixed state which consists of two Bell-like states. Furthermore, we also testify that the quantum steering criterion based on the local uncertainty relation is not only superior to the linear steering criterion but also superior to the steering criterion based on the entropic uncertainty relation in our scenario. Our efforts may promote the use of this criterion in quantum information processing tasks.

Experimental verification of the relationship between first-order coherence and linear steerability.

Coherence and steerability are two essential characteristics of quantum systems. For a two-qubit state, the first-order coherence and the maximal violation of linear steering inequality are used to operationally measure the degree of coherence and steerability, respectively. Recently, a complementary relation between first-order coherence and linear steerability has been proposed. In this paper, we report an experimental verification of the complementary relation by preparing biphoton polarization entangled states in an all-optical setup. We propose an operable method for experimental measurement of the first-order coherence and linear steerability and calculate the purity of the initial states by reconstructing the density matrices of them. The experimental results coincide with the theoretical predictions very well, which provides a valuable reference for the application of optical quantum technology.

Spin-orbit X states

We propose an all-optical setup to produce a wide class of $X$ states with an intense laser beam using spin-orbit modes. In order to characterize such simulated states, we reconstructed the density matrix by simulating spin-orbit tomography and studied the discord and concurrence for different states. The results show very good agreement with theoretical predictions. We also propose two different optical circuits to prepare the single-photon spin-orbit $X$ state.

Non-Markovianity leading to coherence revivals in an open quantum system

Coherence and quantum correlations have been identified as fundamental resources for quantum information tasks. As recently shown, these resources can be interconverted. In multipartite systems, entanglement represents a prominent case among quantum correlations, one which can be activated from coherence. All this makes coherence a key resource for securing the operational advantage of quantum technologies. When dealing with open systems, decoherence hinders full exploitation of quantum resources. Here, we present a protocol that allows reaching the maximal achievable amount of coherence in an open quantum system. By implementing our protocol, or suitable variants of it, coherence losses might be fully compensated, thereby leading to coherence revivals. We provide an experimental proof of principle of our protocol through its implementation with an all-optical setup.