Slow and stopped light systems form an important piece of the photonics puzzle by acting as memory devices. When used with few-photon light levels, these devices are fundamental to applications in quantum information science, quantum computing, and quantum communication. We report on our progress implementing a technique 1 for measuring the quantum state of light that has been stored in a warm-vapor slow-light system. This technique does not require careful mode matching can in fact be used to optimize the measured eld mode without a prior knowledge of the stored light.
Slow and stopped light systems form an important piece of the photonics puzzle by acting as memory devices. When used with few-photon light levels, these devices are fundamental to applications in quantum information science, quantum computing, and quantum communication. We report on our progress implementing a technique 1 for measuring the quantum state of light that has been stored in a warm-vapor slow-light system. This technique does not require careful mode matching can in fact be used to optimize the measured eld mode without a prior knowledge of the stored light.
Quantum information can be transferred from a beam of light to a cloud of atoms and controllably released at a later time. These quantum memory devices are fundamental to applications in quantum information science, quantum computing, and quantum communication. We propose a technique for measuring the quantum state of light that has been stored and released from a quantum memory system. This technique does not require careful mode matching can in fact be used to optimize the measured field mode without a priori knowledge of the stored light.
Quantum information can be transferred from a beam of light to a cloud of atoms and controllably released at a later time. This process forms the basis of many important quantum memory devices that are fundamental to the future of quantum information science, quantum computing, and quantum communication. Prior experiments have stored light in a variety of systems, including cold atom clouds, warm atomic vapor, solid state materials, and optical fibers. To extend these successful investigations, the goal of our research program is to carry out a full characterization of the quantum states of stored-and-retrieved multimode light.
Quantum memories play a pivotal role in establishing long-distance communication by entanglement swapping operations within quantum repeater nodes. Constructing such a quantum memory involves Electromagnetically Induced Transparency (EIT) within atomic vapors at room temperatures to store highly attenuated coherent light pulses down to the level of single photons. The photons may be generated from quantum nodes containing stationary quantum systems, such as atoms or semiconductor quantum dots (QDs). QDs serve as a potent source of quantum light, furnishing bright, precisely timed single photons of exceptional purity. While previous endeavors have demonstrated the integration of QDs with atomic vapors through techniques like “slow light,” the development of a dedicated quantum memory for QDs remains unmatched. In our study, we introduce an EIT quantum memory hosted within warm cesium vapor. Our approach exhibits a good efficiency in storing faint coherent light pulses at the single photon level. Moreover, the measured bandwidth of around 200 MHz approaches the Fourier-limited emission characteristics of QDs. We present initial efforts to match the emission from QDs with our quantum memory and discuss application scenarios of room temperature EIT quantum memories.
Quantum technologies open doors to outstanding applications, at the same time as they pose many scientific challenges. The promise of intrinsically secure communications relies on the implementation of quantum networks. However, noise in quantum channels sets a limit to both the range and the faithfulness of the communication link. To overcome these difficulties, quantum repeater schemes have been proposed to successfully transmit flying qubits (single photons) over long distances. The aim of this project is to advance towards the implementation of a fully functional quantum memory, a key element of any quantum repeater scheme. To do so, a hot rubidium vapor cell was employed, which takes advantage of electromagnetically induced transparency to perform the light storage process, using, in this case, light from a quantum dot. The novelty of the work resides on the fact that never has light from a quantum dot been stored in such a memory device. These objectives implied improving the transmission efficiency (from 5% to 14%) following numerous steps, as well as finding and characterizing a suitable quantum dot sample. The work in hand presents the numerous accomplishments that have been achieved, which set the realization of a quantum repeater very close to our reach.
Today, quantum photonics is one of the leading platforms for the research and development of the quantum information sciences and technologies. It is also the most promising platform for quantum networking protocols. As such, the investigation and characterization of quantum light sources is vital to the future of quantum research. In this thesis document, titled “Multimode Statistical Photonics and Quantum State Tomography for Quantum Networks,” I present my research on the multi-mode statistical properties of classical light sources, with applications to quantum state tomography methods for use in quantum communications and networking protocols. During my time here at LSU, I have worked with my fellow researchers in the quantum photonics group to investigate the quantum dynamics which govern the classical statistical behaviors of stochastically-random light sources. By extracting the correlated multiphoton, multi-mode subsystems of such sources, we have discovered nontrivial, uniquely-quantum behaviors within sources of light which were previously thought to be only classical. I have also developed a robust theoretical framework for describing such sources, utilizing techniques from quantum field theory, which we have shown to be an excellent predictor of experimental measurements. I have then applied these innovations to projects concerning plasmonic nanostructures, quantum imaging, and quantum sensing. Additionally, in collaboration with the National Institute of Standards and Technology (NIST), I have performed an experiment utilizing weak-field interference to prove the correctness of a quantum state tomography method called weak-field homodyne detection, a low-noise procedure which is ideal for quantum communications and networking protocols. As a result, I was able to completely reconstruct a coherent quantum state within the interference mode, and also to obtain some limited information about the remaining modes of that state. Throughout all of this, my research has had a particular focus on multi-mode photonics and its applications to plasmonics and quantum networking, and I believe that the state-tomography protocols and the results concerning stochastically-random quantum light sources will be of use to the quantum information and photonics communities for years to come.
The ability of storing and retrieving quantum states of light is an important experimental challenge in quantum information science. A powerful quantum memory for light is required in a quantum repeater, which would allow long distance (>500km) quantum communications. To be implemented in such application, the quantum memory must allow on-demand readout, with high fidelity and efficiency, and a long storage time. Additionally a multimode capacity (for temporal or spatial modes) would allow multiplexing. Our approaches focus on rare-earth doped crystals, i.e. solid state quantum memory. I present, in this work, our contributions for a solid-state quantum storage, with good performances in every criteria. In particular, I present the preservation of quantum entanglement during the storage, which paves the way for the implementation of quantum memories in quantum repeaters.