Radek Lapkiewicz

Radek Lapkiewicz
University of Warsaw | UW · Institute of Experimental Physics

About

78
Publications
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4,096
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Publications

Publications (78)
Article
Full-text available
Single photons with helical phase structures may carry a quantized amount of orbital angular momentum (OAM), and their entanglement is important for quantum information science and fundamental tests of quantum theory. Because there is no theoretical upper limit on how many quanta of OAM a single photon can carry, it is possible to create entangleme...
Article
Full-text available
Indistinguishable quantum states interfere, but the mere possibility of obtaining information that could distinguish between overlapping states inhibits quantum interference. We present a novel quantum imaging concept that relies on the indistinguishability of the possible sources of a photon that remains undetected. Our experiment uses pair creati...
Article
Full-text available
Significance Entanglement as a fundamental concept of quantum physics is manifested in correlations between particles. The correlation between two particles is usually measured by detecting both of them. Here, we present the results of an experiment based on a unique concept, where the momentum correlation between two photons is measured by detecti...
Article
Full-text available
The principles of quantum optics have yielded a plethora of ideas to surpass the classical limitations of sensitivity and resolution in optical microscopy. While some ideas have been applied in proof-of-principle experiments, imaging a biological sample has remained challenging, mainly due to the inherently weak signal measured and the fragility of...
Article
Full-text available
Fluorescence microscopy is a critical tool across various disciplines, from materials science to biomedical research, yet it is limited by the diffraction limit of resolution. Advanced super-resolution techniques such as localization microscopy and stimulated-emission-depletion microscopy often demand considerable resources. These methods depend he...
Preprint
Full-text available
Dopamine-sensitive neurons are organized in two classes of cells, expressing D1- or D2- types of dopamine receptors, and are often mediating opposing aspects of reward-oriented behaviors. Here, we focused on dopamine-sensitive neurons in the central amygdala - a brain structure critically involved in processing emotion-related stimuli. We discovere...
Preprint
Scattering poses a significant challenge in optical imaging. In microscopy, it leads to progressive degradation of image quality preventing sample examination at increasing depths. As the thickness of the sample increases, the number of photons that can successfully pass through it decreases, leading to a reduced signal and preventing us from obtai...
Preprint
Full-text available
Fluorescence microscopy is a critical tool across various disciplines, from materials science to biomedical research, yet it is limited by the diffraction limit of resolution. Advanced super-resolution techniques such as localization microscopy and stimulated-emission-depletion microscopy often demand considerable resources. These methods depend he...
Preprint
Full-text available
Fluorescence microscopy is a critical tool across various disciplines, from materials science to biomedical research, yet it is limited by the diffraction limit of resolution. Advanced super-resolution techniques such as localization microscopy and stimulated-emission-depletion microscopy often demand considerable resources. These methods depend he...
Article
Full-text available
Efficient measurement of high-dimensional quantum correlations, especially spatial ones, is essential for quantum technologies. We propose and demonstrate an adaptively gated hybrid intensified camera (HIC) that combines the information from a high spatial resolution sensor and a high temporal resolution detector, offering precise control over the...
Article
Full-text available
The local propagation and the energy flux in structured optical fields are often associated with the Poynting vector. However, the local phase gradient (i.e., local wavevector) in monochromatic fields in free space is described by another fundamental quantity: the canonical momentum density. Distributions of the Poynting and canonical momentum dens...
Article
Full-text available
Reprogrammable integrated optics provides a natural platform for tunable quantum photonic circuits, but faces challenges when high dimensions and high connectivity are involved. Here, we implement high-dimensional linear transformations on spatial modes of photons using wavefront shaping together with mode mixing in a multimode fiber, and measure p...
Article
Interferometric methods form the basis of highly sensitive measurement techniques from astronomy to bioimaging. Interferometry typically requires high stability between the measured and reference beams. The presence of rapid phase fluctuations washes out interference fringes, making phase profile recovery impossible. This challenge can be addressed...
Article
Full-text available
M. V. Berry’s work [J. Phys. A 43, 415302 (2010)1751-811310.1088/1751-8113/43/41/415302] highlighted the correspondence between backflow in quantum mechanics and superoscillations in waves. Superoscillations refer to situations where the local oscillation of a superposition is faster than its fastest Fourier component. This concept has been used to...
Preprint
Efficient measurement of high-dimensional quantum correlations, especially spatial ones, is essential for quantum technologies, given their inherent high dimensionality and easy manipulation with basic optical elements. We propose and demonstrate an adaptively-gated hybrid intensified camera (HIC) that combines the information from a high spatial r...
Preprint
Full-text available
Reprogrammable linear optical circuits are essential elements of photonic quantum technology implementations. Integrated optics provides a natural platform for tunable photonic circuits, but faces challenges when high dimensions and high connectivity are involved. Here, we implement high-dimensional linear transformations on spatial modes of photon...
Preprint
Full-text available
M.V. Berry's work [J. Phys. A: Math. Theor. 43, 415302 (2010)] highlighted the correspondence between backflow in quantum mechanics and superoscillations in waves. Superoscillations refer to situations where the local oscillation of a superposition is faster than its fastest Fourier component. This concept has been used to demonstrate backflow in t...
Article
Measuring entanglement is an essential step in a wide range of applied and foundational quantum experiments. When a two-particle quantum state is not pure, standard methods to measure the entanglement require detection of both particles. We realize a conceptually new method for verifying and measuring entanglement in a class of two-part (bipartite)...
Preprint
Interferometric methods, renowned for their reliability and precision, play a vital role in phase imaging. Interferometry typically requires high coherence and stability between the measured and the reference beam. The presence of rapid phase fluctuations averages out the interferogram, erasing the spatial phase information. This difficulty can be...
Article
Full-text available
The well-known interference pattern of bright and dark fringes was first observed for light beams back in 1801 by Thomas Young. The maximum visibility fringes occur when the irradiance of the two beams is equal, and as the ratio of the beam intensities deviates from unity, fringe visibility decreases. An interesting outcome that might not be entire...
Article
Full-text available
We present a tutorial on the phenomenon of induced coherence without induced emission, and specifically its application to imaging and metrology. It is based on a striking effect where two nonlinear crystals, by sharing a coherent pump and one or two output beams, can induce coherence between the other two output beams. This can be thought of as a...
Preprint
Full-text available
The well-known interference pattern of bright and dark fringes was first observed for light beams back in 1801 by Thomas Young. The maximum visibility fringes occur when the irradiance of the two beams is equal, and as the ratio of the beam intensities deviates from unity, fringe visibility decreases. An interesting outcome that might not be entire...
Preprint
Full-text available
We present a tutorial on the phenomenon of induced coherence without induced emission, and specifically its application to imaging and metrology. It is based on a striking effect where two nonlinear crystals, by sharing a coherent pump and one of two output beams each, can induce correlations between the other two individual, non-interacting beams....
Article
Full-text available
Quantum imaging with undetected photons is a recently introduced technique that goes significantly beyond what was previously possible. In this technique, images are formed without detecting the light that interacted with the object that is imaged. Given this unique advantage over the existing imaging schemes, it is now of utmost importance to unde...
Conference Paper
We experimentally demonstrate a hybrid camera setup, in which the number of photons detected within each frame can be controlled by gating an image intensifier adaptively, enabling spatially resolved single-photon counting measurements.
Article
Full-text available
Super-resolution microscopy techniques have pushed the limits of resolution in optical imaging by more than an order of magnitude. However, these methods often require long acquisition times as well as complex setups and sample preparation protocols. Super-resolution Optical Fluctuation Imaging (SOFI) emerged over ten years ago as an approach that...
Article
Full-text available
Quantitative characterization of the spatial structure of single photons is essential for free-space quantum communication and quantum imaging. We introduce an interferometric technique that enables the complete characterization of a two-dimensional probability amplitude of a single photon. Importantly, in contrast to methods that use a reference p...
Article
Entanglement verification and measurement is essential for experimental tests of quantum mechanics and also for quantum communication and information science. Standard methods of verifying entanglement in a bipartite mixed state require detection of both particles and involve coincidence measurement. We present a method that enables us to verify an...
Preprint
Full-text available
Quantum imaging with undetected photons is a recently introduced technique that goes significantly beyond what was previously possible. In this technique, images are formed without detecting the light that interacted with the object that is imaged. Given this unique advantage over the existing imaging schemes, it is now of utmost importance to unde...
Article
Full-text available
Super-resolution optical microscopy is a rapidly evolving scientific field dedicated to imaging sub-wavelength-sized objects, leaving its mark in multiple branches of biology and technology. While several super-resolution optical microscopy methods have become a common tool in life science imaging, new methods, supported by cutting-edge technology,...
Preprint
Entanglement verification and measurement is essential for experimental tests of quantum mechanics and also for quantum communication and information science. Standard methods of verifying entanglement in a bipartite mixed state require detection of both particles and involve coincidence measurement. We present a method that enables us to verify an...
Preprint
Entanglement is a fundamental feature of quantum mechanics, considered a key resource in quantum information processing. Measuring entanglement is an essential step in a wide range of applied and foundational quantum experiments. When a two-particle quantum state is not pure, standard methods to measure the entanglement require detection of both pa...
Preprint
Full-text available
Quantitative characterization of the spatial structure of single photons is essential for free-space quantum communication and quantum imaging. We introduce an interferometric technique that enables the complete characterization of a two-dimensional probability amplitude of a single photon. Importantly, in contrast to methods which use a reference...
Preprint
Full-text available
Super-resolution optical microscopy is a rapidly evolving scientific field dedicated to imaging sub-wavelength sized objects, leaving its mark in multiple branches of biology and technology. While several super-resolution optical microscopy methods have become a common tool in life science imaging, new methods, supported by cutting-edge technology,...
Conference Paper
Single photon sensitive cameras are extensively used in modern optics. Intensified cameras provide high spatial resolution and sub-nanosecond gating possibility, but suffer from low duty cycle and high acquisition times when used for observation of random processes. We propose and experimentally demonstrate a setup in which the number of photons de...
Conference Paper
We reintroduce the concept of SOFISM and discuss its practical aspects. We demonstrate that supplying a confocal microscope with a SPAD array detector enables super-resolution imaging relying on fluorophore blinking within reasonable dwell times.
Article
Full-text available
Interference of two beams produced at separate biphoton sources was first observed more than two decades ago. The phenomenon, often called “induced coherence without induced emission,” has recently gained attention after its applications to imaging, spectroscopy, and measuring biphoton correlations have been discovered. The sources used in the corr...
Conference Paper
We introduce and demonstrate an experimental technique based on one photon interference for complete characterization of an arbitrary two dimensional spatial structure of a single photon beam without using any reference photon beam.
Conference Paper
We demonstrate an approach for super-resolution imaging by combining fluorophore fluctuations analysis with a confocal detector array setup. This combination facilitates obtaining high resolution images without a complex experimental setup and prohibitively long data acquisition.
Conference Paper
We experimentally demonstrate a phase imaging technique which is resistant to time dependent phase fluctuations based on measuring intensity correlations instead of intensities. The method allows for long measurements, advantageous under low photon fluxes.
Conference Paper
We introduce and experimentally demonstrate a self-referenced interferometric technique which enables complete characterization of an arbitrary 2D spatial structure of a single photon relying on the fact that a single photon can interfere with itself.
Preprint
Full-text available
The principles of quantum optics have yielded a plethora of ideas to surpass the classical limitations of sensitivity and resolution in optical microscopy. While some ideas have been applied in proof-of-principle experiments, imaging a biological sample has remained challenging mainly due to the inherently weak signal measured and the fragility of...
Article
Full-text available
Interference of two beams produced at separate biphoton sources was first observed more than two decades ago. The phenomenon, often called "induced coherence without induced emission", has recently gained attention after its applications to imaging, spectroscopy, and measuring biphoton correlations have been discovered. The sources used in the corr...
Article
Full-text available
Interference phenomena play a fundamental role in physics, and interferometric techniques have helped advance science and technology significantly. In this Letter, we observe spatial fringes in the interference of two beams, which are controlled by a third beam through the phenomenon of induced coherence without induced emission. We show that the i...
Preprint
We report a measurement of the transverse momentum correlation between two photons by detecting only one of them. Our method uses two identical sources in an arrangement, in which the phenomenon of induced coherence without induced emission is observed. In this way, we produce an interference pattern in the superposition of one beam from each sourc...
Preprint
We observe spatial fringes in the interference of two beams, which are controlled by a third beam through the phenomenon of induced coherence without induced emission. We show that the interference pattern depends on the alignment of this beam in an analogous way as fringes created in a traditional division-of-amplitude interferometer depend on the...
Article
We show that it is possible to generate a novel single-photon fringe pattern by using two spatially separated identical bi-photon sources. The fringes are similar to the ones observed in a Michelson interferometer and possess certain remarkable properties with potential applications. A striking feature of the fringes is that although the pattern is...
Preprint
We show that it is possible to generate a novel single-photon fringe pattern by using two spatially separated identical bi-photon sources. The fringes are similar to the ones observed in a Michelson interferometer and possess certain remarkable properties with potential applications. A striking feature of the fringes is that although the pattern is...
Article
Full-text available
Quantum mechanics predicts a number of at first sight counterintuitive phenomena. It is therefore a question whether our intuition is the best way to find new experiments. Here we report the development of the computer algorithm Melvin which is able to find new experimental implementations for the creation and manipulation of complex quantum states...
Conference Paper
We create a novel single-photon fringe pattern using non-degenerate photon pairs. Although one photon in each pair is not detected, its wavelength characterizes the fringe shift. The fringe visibility depends on the two-photon momentum correlation.
Article
Full-text available
Partial polarization is the manifestation of the correlation between two mutually orthogonal transverse field components associated with a light beam. We show both theoretically and experimentally that the origin of this correlation can be purely quantum mechanical. We perform a two-path first-order (single photon) interference experiment and demon...
Article
Full-text available
A novel quantum imaging technique has recently been demonstrated in an experiment, where the photon used for illuminating an object is not detected; the image is obtained by interfering two beams, none of which ever interacts with the object. Here we present a detailed theoretical analysis of the experiment. We show that the object information is p...
Article
Complex transverse spatial modes of photons are very interesting for both, foundations and applications of quantum information. In a first experiment, we generate two-dimensional bi-partite entanglement where each photon carries an orbital angular momentum of a quantum number up to 300. Secondly, we demonstrate (100 × 100)-dimensional entanglement,...
Article
In the study of systems that cannot be described classically, the Wigner inequality, has received only a small amount of attention. In this paper we extend the Wigner inequality\char22{}originally derived in 1969\char22{}and show how it may be used to contradict local realism with only coincidence detections in the absence of two-outcome measuremen...
Conference Paper
We present the results of an experiment in which the degree of polarization of a photon beam emerging from the output of a two-path interferometer is controlled by modulating the interferometric path information.
Article
Full-text available
Photonics has become a mature field of quantum information science, where integrated optical circuits offer a way to scale the complexity of the set-up as well as the dimensionality of the quantum state. On photonic chips, paths are the natural way to encode information. To distribute those high-dimensional quantum states over large distances, tran...
Article
Full-text available
Significance Quantum entanglement is one of the key features of quantum mechanics. Quantum systems are the basis of new paradigms in quantum computation, quantum cryptography, or quantum teleportation. By increasing the size of the entangled quantum system, a wider variety of fundamental tests as well as more realistic applications can be performed...
Conference Paper
We present a Bell inequality that does not require two-outcome measurements. It is based on an inequality originally derived by Wigner, extending it such that no assumptions other than local-realism, fair-sampling, and freedom-of-choice are necessary.
Article
Full-text available
Indistinguishability of photons that need not be detected results in a novel paradigm of quantum information processing. This confirms that for quantum interference it is important whether two possibilities could in principle be distinguished independent of detection.
Article
Full-text available
We report the efficient creation and detection of hybrid entanglement between one photon's polarization and another photon's complex transverse polarization pattern. The polarization measurement of the first photon triggers a polarization sensitive imaging of its partner photon, the vector photon, using a single-photon sensitive camera. Thereby, we...
Conference Paper
We developed a method to create custom tailored photonic entanglement of complex spatial modes. By taking advantage of the high timing and spatial resolution of an intensified CCD camera, we investigate the properties of the entangled photon pair.
Article
Full-text available
Recent experiments and theory have further illuminated the concept of "quantum contextuality". In this paper we take an inequality - the Pentagram (or KCBS) inequality, which is violated by an unentangled spin-1 system - and given a relaxed assumption of non-contextuality show that a hidden variable model may be constructed that replicates exactly...
Article
Full-text available
The orbital angular momentum quantum number of Laguerre-Gauss beams has received an explosively increasing amount of attention over the past twenty years. However, often overlooked is the so-called radial number of these beams. We present a derivation of the differential operator formalism of this "forgotten" quantum number. We then draw some conne...
Article
Full-text available
Quantum Entanglement is widely regarded as one of the most prominent features of quantum mechanics and quantum information science. Although, photonic entanglement is routinely studied in many experiments nowadays, its signature has been out of the grasp for real-time imaging. Here we show that modern technology, namely triggered intensified charge...
Article
Full-text available
In a recent paper [arXiv:1301.2887] Ahrens et al. claim that our "(...) experiment on qutrits does not test Klyachko et al.'s inequality, but an inequality with extra correlations" and that the "(...) experiment cannot be considered a proper test of a noncontextuality inequality, since the same observable is measured with different setups in differ...
Article
Full-text available
In the study of systems that can not be explained classically, the Wigner inequality, has received only a small amount of attention. In this paper we extend the Wigner inequality - originally derived in 1969 - and show how it may be used to contradict local realism with only coincidence detections in the absence of two-outcome measurements - that i...
Article
Full-text available
Integrated photonic circuits offer the possibility for complex quantum optical experiments in higher-dimensional photonic systems. However, the advantages of integration and scalability can only be fully utilized with the availability of a source for higher-dimensional entangled photons. Here, a novel fiber integrated source for path-entangled phot...