We report an experiment of which-way information and a quantum eraser based on polarization-controlled interference of two twisted light beams carrying high orbital angular momentum (OAM) up to ℓ=±50 and ±100, respectively. By changing the polarization plane of one OAM beam from 0° to 90° with respect to that of the other OAM beam, we observe the gradual disappearance of the interference petal-like patterns into the noninterference single bright rings. Subsequently, we use the eraser of a diagonal polarizer to retrieve the characteristic petal-like interference. The experimental results can be well explained in the frame of single-photon Greenberger-Horne-Zeilinger-like (GHZ-like) entanglement. Our work may be beneficial to understanding the wave-particle duality of light.
We report an experiment of which-way information and a quantum eraser based on polarization-controlled interference of two twisted light beams carrying high orbital angular momentum (OAM) up to ℓ=±50 and ±100, respectively. By changing the polarization plane of one OAM beam from 0° to 90° with respect to that of the other OAM beam, we observe the gradual disappearance of the interference petal-like patterns into the noninterference single bright rings. Subsequently, we use the eraser of a diagonal polarizer to retrieve the characteristic petal-like interference. The experimental results can be well explained in the frame of single-photon Greenberger-Horne-Zeilinger-like (GHZ-like) entanglement. Our work may be beneficial to understanding the wave-particle duality of light.
Youngs double slit experiment is one of the most celebrated achievements in quantum and classical optics; it provides experimental proof of the wave-particle duality of light. When the paths of the double slit are marked with orthogonal polarizations, the path information is revealed and no interference pattern is observed. However, the path information can be erased with a complimentary analysis of the polarization. Here we use hybrid entanglement between photons carrying orbital angular momentum and polarization to show that, just as in Young's experiment, the paths (OAM) marked with polarization do not lead to interference. However, when introducing the eraser (polarizer) which projects the polarization of one of the entangled photons onto a complementary polarization basis, the OAM (paths) are allowed to interfere, leading to the formation of azimuthal fringes whose frequency is proportional to the OAM content carried by the photon.
The quantum eraser effect exemplifies the distinctive properties of quantum mechanics that challenge classical intuition and reveal the wave-particle duality of light.Whether the photon exhibits particle-like or wave-like behavior depends on whether the path information is discernible.In this paper, we propose a novel quantum eraser scheme that utilizes photonic phase structures as the which-way indicator.This scheme is implemented using a Mach-Zehnder interferometer (MZI), where one arm is configured with orbital angular momentum (OAM) to establish predetermined which-way information.Consequently, at the output ports of the MZI, the photon displays particle-like characteristics when the which-way information is retained.However, the introduction of an additional spiral phase plate (SPP) to eliminate the phase structure from the output photon of the MZI unveils distinct interference patterns.This result enhances our understanding of the quantum erasure effect.
Quantum erasers with paths in the form of physical slits have been studied extensively and proven instrumental in probing wave-particle duality in quantum mechanics. Here we replace physical paths (slits) with abstract paths of orbital angular momentum (OAM). Using spin-orbit hybrid entanglement of photons, we show that the OAM content of a photon can be erased with a complementary polarization projection of one of the entangled pair. The result is the (dis)appearance of azimuthal fringes based on whether the ``which-OAM'' information was erased. We extend this concept to a delayed measurement scheme and show that the OAM information and fringe visibility are complementary.
ABSTRACT The complementarity principle, as the cornerstone of quantum information, is both counterintuitive and inherently characterized by mutual exclusivity. In this work, we construct a quantum erasure scheme utilizing polarization and orbital angular momentum (OAM) two‐photon hybrid entanglement, and develop a first‐photon physics‐enhanced dual‐branch residual attention network with physical constraints to visualize the disappearance and reappearance of single‐photon petal‐like interference patterns, with much fewer than one photon per pixel and without the need for exhaustive detection of all OAM modes. This work not only helps people to deepen their intuitive understanding of the which‐path concept in quantum mechanics, but also advances quantum imaging in the visualization of subtle changing quantum phenomena.
Summary form only given. The orbital angular momentum (OAM) of light has raised a great deal of applications [1], ranging from the trapping of particles, the driving of optical micromachines to applications in astrophysics studies. In quantum optics, twisted single-photons have also been identified as promising carriers for the implementation of various quantum information protocols. They indeed offer the possibility to encode and process information in high-dimensional Hilbert spaces and could enable to reach higher efficiencies and enhanced information capacity. For further applications in quantum networks involving light-matter interfaces, a critical capability is the ability to reversibly map OAM into and out of atomic memories. While the storage of bright beams of light in Laguerre-Gaussian modes has been reported in the past few years [2, 3], we report here the first demonstration of storage in the single-photon regime [4]. The experimental realization proceeds in the following way. First, LG modes are generated using a spatial light modulator. These modes, which are weak coherent states at the single-photon level, are then mapped into an ensemble of cold cesium atoms in a magneto-optical trap using the dynamic electromagnetically-induced transparency (EIT) protocol. The signal quantum properties, including its OAM, are expected to be transferred to the atomic medium and can be stored for a programmable time, limited by the lifetime of the atomic coherence. After this reversible storage, unlike for bright beams, the detection of twisted single-photons cannot be performed by imaging on a CCD camera. Here we have chosen to work with a combination of a computergenerated hologram, which adds or subtracts one unity of OAM, and a single-mode fiber to implement a mode discriminator. In our experiment, the output mode is actually split on a 50/50 beam splitter and one discriminator is installed in each of the two output paths so that we can quantify both the LG+1 and LG-1 components of the retrieved light. We stored and retrieved LG+1 and LG-1 modes. As can be seen in fig. 1, detection events in the detection path with l opposite to the one of the incoming mode are negligible, within the distinction ratio. For both modes, the overall storage and retrieval efficiency is (16 ± 2%). We thus demonstrated that such pulses carrying OAM can be stored in the single-photon regime into and out the ensemble with preserved handedness of the helical phase structure. Mapping of a TEM10 mode, i.e. an equal-weight superposition of LG+1 and LG-1 modes was also performed. Within our experimental precision, the achieved storage and retrieval efficiency is the same here each LG components than for the individual storage presented previously. Further works should include reconstruction of a full density matrix, including coherences not measured here, and the calculation of process fidelity. We implemented a sophisticated detection technique based on a Mach-Zehnder interferometer. Preliminary results will be reported. Extensions to higher alphabets for the realization of high-dimensional quantum information networks is also work for future.
Optical orbital angular momentum (OAM) is a special property of photons and has evoked research onto the light–matter interaction in both classical and quantum regimes. In classical optics, OAM is related to an optical vortex with a helical phase structure. In quantum optics, photons with a twisted or helical phase structure will carry a quantized OAM. To our knowledge, however, so far, no experiment has demonstrated the fundamental property of the OAM at the single-photon level. In this Letter, we have demonstrated the average photon trajectories of twisted photons in a double-slit interference. We have experimentally captured the double-slit interference process of twisted photons by a time-gated intensified charge-coupled device camera, which is trigged by a heralded detection. Our work provides new perspectives for understanding the micro-behaviors of twisted particles and enables new applications in imaging and sensing.