Qudits with a large Hilbert space to host quantum information are widely utilized in various applications, such as quantum simulation and quantum computation, but the manipulation and scalability of qudits still face challenges. Here, we propose a scheme to directly and locally transfer quantum information from multiple atomic qubits to a single qudit and vice versa in an optical cavity. With the qubit–qudit interaction induced by the cavity, our scheme can transfer quantum states efficiently and measurement-independently. In addition, this scheme can robustly generate a high-dimensional maximal entangled state with asymmetric particle numbers, showing its potential in realizing an entanglement channel. Such an information interface for qubits and qudit may have enlightening significance for future research on quantum systems in hybrid dimensions.
Qudits with a large Hilbert space to host quantum information are widely utilized in various applications, such as quantum simulation and quantum computation, but the manipulation and scalability of qudits still face challenges. Here, we propose a scheme to directly and locally transfer quantum information from multiple atomic qubits to a single qudit and vice versa in an optical cavity. With the qubit–qudit interaction induced by the cavity, our scheme can transfer quantum states efficiently and measurement-independently. In addition, this scheme can robustly generate a high-dimensional maximal entangled state with asymmetric particle numbers, showing its potential in realizing an entanglement channel. Such an information interface for qubits and qudit may have enlightening significance for future research on quantum systems in hybrid dimensions.
Qudits with a large Hilbert space to host quantum information are widely utilized in various applications, such as quantum simulation and quantum computation, but the manipulation and scalability of qudits still face challenges. Here, we propose a scheme to directly and locally transfer quantum information from multiple atomic qubits to a single qudit and vice versa in an optical cavity. With the qubit-qudit interaction, our scheme can transfer quantum states efficiently and measurement-independently. In addition, this scheme can be extended to the non-local case, where a high-dimensional maximal entangled state with asymmetric particle numbers can be robustly generated for realizing long-distance quantum communication. Such an information interface for qubits and qudit may have enlightening significance for future research on quantum systems in hybrid dimensions.
Quantum entanglement is a fundamental resource for quantum information processing and is widely used in quantum communication, quantum computation and quantum metrology. Early research on quantum entanglement mainly focus on qubit states, but in recent years, more and more research has begun to focus on high-dimensional entangled states. Compared with qubit entangled states, higher-dimensional entangled states have a larger information capacity and the potential to realize more complex quantum applications. In this Letter, we have experimentally prepared a special high-dimensional entangled state, the so-called three-photon asymmetric maximally entangled state, which consists of two two-dimensional photons and one four-dimensional photon. Using this asymmetric maximally entangled state as a resource, we have also implemented a proof-of-principle quantum teleportation experiment, realizing the transfer of quantum information from two qubits to a single ququart. The fidelities of the quantum teleportation range from 0.79 to 0.86, which are well above both the optimal single-copy ququart state-estimation limit of 2/5 and maximal qutrit-ququart overlap of 3/4, thus confirming a genuine and nonclassical four-dimensional teleportation. The asymmetric entangled state realized here has the potential to be used as a quantum interface in future quantum networks, allowing quantum information transfer between quantum objects of different dimensions via the quantum teleportation protocol demonstrated in this work.
Quantum entanglement is crucial for quantum information processing, prominently used in quantum communication, computation, and metrology. Recent studies have shifted toward high-dimensional entangled states, offering greater information capacity and enabling more complex applications. Here, we experimentally prepared a three-photon asymmetric maximally entangled state, comprising two two-dimensional photons and one four-dimensional photon. Using this state, we conducted a proof-of-principle experiment, successfully transferring a four-dimensional quantum state from two photons to another photon with fidelities ranging from 0.78 to 0.86. These results exceed theoretical limits, demonstrating genuine four-dimensional quantum state transfer. The asymmetric entangled state demonstrated here holds promise for future quantum networks as a quantum interface facilitating information transfer across quantum systems with different dimensions.
Quantum mechanics provides a disembodied way to transfer quantum information from one quantum object to another. In theory, this quantum information transfer can occur between quantum objects of any dimension, yet the reported experiments of quantum information transfer to date have mainly focused on the cases where the quantum objects have the same dimension. Here, we theoretically propose and experimentally demonstrate a scheme for quantum information transfer between quantum objects of different dimensions. By using an optical qubit-ququart entangling gate, we observe the transfer of quantum information between two photons with different dimensions, including the flow of quantum information from a four-dimensional photon to a two-dimensional photon and vice versa. The fidelities of the quantum information transfer range from 0.700 to 0.917, all above the classical limit of 2/3. Our work sheds light on a new direction for quantum information transfer and demonstrates our ability to implement entangling operations beyond two-level quantum systems.
A qudit (d-level quantum system) has a large Hilbert space and thus can be used to achieve many quantum information and communication tasks. Here, we propose a method to transfer arbitrary d-dimensional quantum states (known or unknown) between two superconducting transmon qudits coupled to a single cavity. The state transfer can be performed by employing resonant interactions only. In addition, quantum states can be deterministically transferred without measurement. Numerical simulations show that high-fidelity transfer of quantum states between two superconducting transmon qudits (d ≤ 5) is feasible with current circuit QED technology. This proposal is quite general and can be applied to accomplish the same task with natural or artificial atoms of a ladder-type level structure coupled to a cavity or resonator.
Quantum information science possesses promising potentialities for developing new secure and efficient ways to transfer and process information. Prodigious efforts have been and are being devoted, however, a scalable architecture is still a considerable challenge. Among the potential candidates, photons are assumed to be good carriers, and neutral atoms good hosts. In this thesis, photon-matter entanglement sources, which exploit the advantages of both, are employed to demonstrate a teleportation between two atomic-ensemble quantum memory nodes and an efficient entanglement swapping, which are essential for scalable quantum networks. Later, the entanglement source is further developed, and an active feedforward one-way quantum computation is presented \nwith stationary quantum memories, which are necessary for scalable quantum computers. To fulfill another feature of scalability, the ease of integration, ultracold atoms in \ntwo-dimensional optical superlattices are studied and an experiment is designed to generate four-qubit entangled states. With the help of the photon-matter entanglement \nsources, serving as quantum memories and nodes of quantum networks, realization of large-scale quantum networks is foreseeable. Meanwhile, by applying controllable interactions, large entangled states could be generated in optical superlattices, which might help to construct quantum processors that outperform the classical counterparts.