We present a hybrid scheme for quantum computation that combines the modular structure of elementary building blocks used in the circuit model with the advantages of a measurement-based approach to quantum computation. We show how to construct optimal resource states of minimal size to implement elementary building blocks for encoded quantum computation in a measurement-based way, including states for error correction and encoded gates. The performance of the scheme is determined by the quality of the resource states, where within the considered error model a threshold of the order of 10% local noise per particle for fault-tolerant quantum computation and quantum communication.
We present a hybrid scheme for quantum computation that combines the modular structure of elementary building blocks used in the circuit model with the advantages of a measurement-based approach to quantum computation. We show how to construct optimal resource states of minimal size to implement elementary building blocks for encoded quantum computation in a measurement-based way, including states for error correction and encoded gates. The performance of the scheme is determined by the quality of the resource states, where within the considered error model a threshold of the order of 10% local noise per particle for fault-tolerant quantum computation and quantum communication.
We investigate measurement-based quantum communication with noisy resource states that are generated by entanglement purification. We consider the transmission of encoded information via noisy quantum channels using a measurement-based implementation of encoding, error correction, and decoding. We show that such an approach offers advantages over direct transmission, gate-based error correction, and measurement-based schemes with direct generation of resource states. We analyze the noise structure of resource states generated by entanglement purification and show that a local error model, i.e., noise acting independently on all qubits of the resource state, is a good approximation in general, and provides an exact description for Greenberger-Horne-Zeilinger states. The latter are resources for a measurement-based implementation of error-correction codes for bit-flip or phase-flip errors. This provides an approach to link the recently found very high thresholds for fault-tolerant measurement-based quantum information processing based on local error models for resource states with error thresholds for gate-based computational models.
Circuit-based quantum computing (CBQC) has far remained the most intuitive and experimentally mature model of universal quantum computation, serving as the basis for today’s noisy intermediate-scale quantum (NISQ) devices and emerging fault-tolerant quantum computation (FTQC) due to its well-developed control and error-correction techniques. Nevertheless, scalability challenges and suitability to photonic platforms have motivated the exploration of alternative computational models such as measurement-based quantum computing (MBQC), which separates entanglement generation from actual computation and is considered more natural for scalable and distributed architectures. More recently, fusion-based quantum computation (FBQC), and in particular its encoded variant (EFBQC), have been proposed to alleviate many of the practical limitations of traditional MBQC by using constant-size resource states and encoded fusion operations with controllable failure behavior, thus improving practicality, flexibility, and fault-tolerance. Motivated by these potential advantages of measurement-based approaches while recognizing the continued prominence and circuit-level versatility of CBQC, in this work, we propose a hybrid approach that combines CBQC with (E)FBQC to improve long-range connectivity and Clifford-dominated subroutine execution under threshold-compatible operating conditions, enabling higher performance in the context of fault tolerance and architectural scalability. In detail, we propose an encoded-fusion- assisted teleportation (EFAT) mechanism, with two configurations for different scenarios: (1) the Minimal Hybrid, in which (E)FBQC acts as a logical entanglement bus that supplies encoded Bell pairs for teleportation-based connectivity between CBQC modules, thus replacing distance-dependent routing with teleportation and reducing routing overhead when routing dominates the logical schedule, while remaining compatible with the derived surface-code threshold condition; (2) the Extended Hybrid, in which (E)FBQC additionally participates in the computation alongside CBQC nodes, so that encoded cluster fragments can be used to execute Clifford subroutines in constant depth. Our performance analysis shows that the Minimal Hybrid can reduce routing-dominated logical depth while remaining compatible with the derived fault-tolerance condition, whereas the Extended Hybrid can further compress Clifford-dominated subroutines and may improve the temporal scheduling of magic-state supply, at the expense of higher photonic throughput and tighter synchronization requirements. Together, these results indicate a practical route toward scalable, modular, and fault-tolerant quantum computing based on encoded-fusion-assisted hybrid architectures.
The standard primitives of quantum computing include deterministic unitary entangling gates, which are not natural operations in many systems including photonics. Here, we present fusion-based quantum computation, a model for fault tolerant quantum computing constructed from physical primitives readily accessible in photonic systems. These are entangling measurements, called fusions, which are performed on the qubits of small constant sized entangled resource states. Probabilistic photonic gates as well as errors are directly dealt with by the quantum error correction protocol. We show that this computational model can achieve a higher threshold than schemes reported in literature. We present a ballistic scheme which can tolerate a 10.4% probability of suffering photon loss in each fusion, which corresponds to a 2.7% probability of loss of each individual photon. The architecture is also highly modular and has reduced classical processing requirements compared to previous photonic quantum computing architectures.
Quantum error correction is an essential tool for performing reliable quantum information processing tasks under noisy circumstances, and is attracting growing attention today as a crucial element for realizing the fault-tolerant quantum computer. In this article, we introduce two cutting-edge quantum error correction techniques for implementing fault-tolerant quantum computation: the hybrid approach and the fusion-based quantum computation. The hybrid quantum computing utilizes hybrid qubits which combine the advantages of continuous-variable and discrete-variable qubits. The fusion-based quantum error correction offers a way, specialized for photonic quantum information processing, toward fault tolerance based on two-qubit measurement, known as fusion. We demonstrate by numerical simulations that our methods achieve the increased loss threshold and the improved resource efficiency compared to previous photonic proposals.
We introduce an adaptable and modular hybrid architecture designed for fault-tolerant quantum computing. It combines quantum emitters and linear-optical entangling gates to leverage the strength of both matter-based and photonic-based approaches. A key feature of the architecture is its practicality, grounded in the utilisation of experimentally proven optical components. Our framework enables the execution of any quantum error correcting code, but in particular maintains scalability for low-density parity check codes by exploiting built-in non-local connectivity through distant optical links. To gauge its efficiency, we evaluated the architecture using a physically motivated error model. It exhibits loss tolerance comparable to existing all-photonic architecture but without the need for intricate linear-optical resource-state-generation modules that conventionally rely on resource-intensive multiplexing. The versatility of the architecture also offers uncharted avenues for further advancing performance standards.
Quantum computation provides us with a new form of information processing that surpasses current computer technology.In a new model of quantum computation, measurement-based quantum computation, the computation proceeds via simple measurements on previously prepared quantum entangled states.This model has attracted attention for its good potential for realizing quantum computers.This article reviews the basic concepts of measurement-based quantum computation and the elegant fault-tolerant system called topological one-way quantum computation.