14 results about "Quantum error correction" patented technology

The application provides a quantum bit loss identification and quantum error correction method and system, the method comprising: extracting a space-time correlation feature from an obtained multi-round stabilizer measurement sequence; identifying a persistent random flicker mode caused by quantum bit loss according to the space-time correlation feature, and determining a logical decoding result and a quantum bit loss prediction result. The application can simultaneously realize logical decoding and quantum bit loss position identification, and improve the decoding accuracy and overall reliability of a quantum error correction system in a bit loss noise environment.

A quantum computing system and a method of performing a quantum error correction code are disclosed. A determination is made that a leakage event has occurred at a quantum device. A plurality of decoding hypergraph hyperedges potentially affected by the leakage event are determined. The plurality of decoding hypergraph hyperedges are adjusted in accordance with the leakage event.

Error-corrected quantum computation using transversal gates and correlated decoding is provided. A first and second logical qubit is encoded into physical qubits according to a quantum error correcting code. Based on the quantum error correcting code, a bipartite decoding graph is constructed corresponding to the first and the second logical qubits, the bipartite decoding graph comprising a plurality of detector nodes and a plurality of error nodes, each error node corresponding to an error mechanism. A transversal gate is applied to the first and the second logical qubits. Syndrome measurement of the first and the second logical qubits is performed. For each of the plurality of detector nodes affected by the corresponding error mechanism of one of the plurality of error nodes, an edge is generated on the bipartite decoding graph therebetween. A physical error configuration is determined from the bipartite decoding graph.

This invention relates to a quantum error correction method and related equipment. The method includes: acquiring discrete syndrome measurement sequences generated by a quantum processor based on surface codes over multiple consecutive error correction cycles; inputting the discrete syndrome measurement sequences into a causal convolutional neural network to output error prediction information for the next error correction cycle, the error prediction information including the probability distribution of qubit errors; determining a set of high-risk qubits for the next error correction cycle based on the probability distribution; pre-constructing a restricted decoding space for the next error correction cycle based on the set of high-risk qubits; in the next error correction cycle, preferentially performing error chain matching within the restricted decoding space; if no error chain satisfying the verification condition is found within the restricted decoding space, backtracking to the full search space for matching; and outputting error correction operation instructions based on the matching results. This method at least partially solves the problems of poor quantum error correction performance and low efficiency in related quantum error correction methods.

A method for training a layered belief propagation-based deep learning model for decoding a quantum error correction code, according to an embodiment of the present invention, comprises the steps of: initializing a weight assigned to the deep learning model including at least one neural belief propagation (NBP) model; and training the deep learning model so as to minimize a loss function determined in consideration of layered constraints and degeneracy, wherein the deep learning model includes at least one first deep learning model designed by concatenating the at least one NBP model by the number of first layers, and the at least one first deep learning model is configured by being concatenated by the number of second layers corresponding to a preset number of repetitions.

The present disclosure relates to methods for measurement-free fault-tolerant quantum computing. One method comprises preparing, based on a quantum error correction code, a set of three or more logical qubits in an initial state, wherein each logical qubit comprises a plurality of physical qubits. The method also comprises performing a fault-tolerant logical entangling gate on the three or more logical qubits. The present disclosure further relates to a quantum computing device and a computer program.

Error-corrected quantum computation using transversal gates and correlated decoding is provided. A first and second logical qubit is encoded into physical qubits according to a quantum error correcting code. Based on the quantum error correcting code, a bipartite decoding graph is constructed corresponding to the first and the second logical qubits, the bipartite decoding graph comprising a plurality of detector nodes and a plurality of error nodes, each error node corresponding to an error mechanism. A transversal gate is applied to the first and the second logical qubits. Syndrome measurement of the first and the second logical qubits is performed. For each of the plurality of detector nodes affected by the corresponding error mechanism of one of the plurality of error nodes, an edge is generated on the bipartite decoding graph therebetween. A physical error configuration is determined from the bipartite decoding graph.

Techniques for reducing a syndrome density of a plurality of rounds of syndrome measurements following a first decoding stage (e.g., via a local decoder) for quantum error correction of circuit-level noise within quantum surface codes are disclosed. Such techniques for reducing syndrome density may include syndrome collapse and / or vertical cleanup techniques. In a syndrome collapse technique, a measurement results volume may be partitioned into sheets and the respective sheets collapsed, causing vertical pairs of highlighted vertices to be removed. In a vertical cleanup technique, vertical pairs of highlighted vertices may be removed directly from a matching graph following a first decoding stage. Following the removal of vertical pairs of highlighted vertices, the measurement results are then decoded in a second, global decoding stage. Such techniques allow for fast decoding throughout and low latency times for error correction of rounds of syndrome measurements for quantum algorithms implemented using quantum surface codes.

The application discloses a kind of processing method, device, terminal and medium of quantum error correction syndrome data stream, the method comprises: based on the state data of alignment after corresponding measurement and control instrument, obtain comprehensive feature vector;Based on the preset health threshold, the pure clean sparse feature vector is obtained by dead bit filtering processing to the comprehensive feature vector;Based on the preset priority coding tree, the feature extraction result is obtained by sparse feature extraction processing to the pure clean sparse feature vector;Based on the bandwidth characteristics of the fixed bit width block transmission bus corresponding to processing system and the preset message structure, the target high-bandwidth utilization rate aggregation message is obtained by processing the feature extraction result.The application aims to realize the hardware level compression and cleaning processing to mass quantum error correction syndrome data stream, to reduce the bandwidth demand of measurement and control data link bus.

A system comprises a separating component that separates a decoder matrix, representing node units of a quantum error correction process, into a first part and a second part, by executing a cut through a selected node unit, of the node units, and a decoding component that decodes a syndrome, of the quantum error correction process, by directing evaluation of the syndrome by the first part independent from evaluation of the syndrome by the second part.

This quantum error detection device generates a logical state |+⟩ L, 1 of a first quantum error detection code that is a quantum error detection code representing one logical qubit by n1 physical qubits and is a quantum error detection code having a code distance d1. The quantum error detection device executes a logical Rz rotation gate operation of the first quantum error detection code with respect to the logical state |+⟩ L, 1 of the first quantum error detection code, thereby generating a logical state |+θ⟩ L, 1 of the first quantum error detection code. The quantum error detection device executes a sequence of unitary quantum gate operations with respect to the logical state |+θ⟩ L, 1 of the first quantum error detection code, thereby converting the logical state |+θ⟩ L, 1 of the first quantum error detection code into a second quantum error detection code representing one logical qubit by n2 (n2 > n1) physical qubits. The quantum error detection device acquires an error syndrome of a logical state |+θ⟩ L, 2 of the second quantum error detection code.

A method, system, and apparatus for predicting the occurrence of errors in quantum computing. In one embodiment, the method includes updating the edge weights of a second quantum error correction detector graph by performing a local search of a first quantum error correction detector graph, wherein the local search includes, for each detection event in the first quantum error correction detector graph, reweighting complementary edges in the second quantum error correction detector graph using a single edge error on the edge connecting the detection event to the nearest other detection event; and performing a decoding process on the second quantum error correction detector graph to compute a decode output of the decoding process, wherein the decode output predicts the occurrence of errors in quantum computing.

According to various embodiments of the present disclosure, a method of operation of a first node in a communication system is provided, comprising: receiving at least one synchronization signal from a second node; receiving control information from the second node; determining one of two entanglement distillation protocols (EDP) based on fidelity information, wherein the two EDPs include a quantum error correcting codes (QECCs) based EDP and a quantum private authentication (QPA) protocol; determining one or more parameters for a plurality of Einstein-Podolsky-Rosen (EPR) states associated with the EDP based on fidelity information; performing the EDP using a measurement of one or more first EPR states among the plurality of EPR states based on one or more parameters; and, based on the result of performing the EDP, preserving one or more unmeasured second EPR states among the plurality of EPR states, performing additional EDP in relation to one or more second EPR states, or discarding the plurality of EPR states and repeating the EDP.

A method for operating a fault-tolerant quantum computing system (QCS), which includes a first set of physical qubits (PQs) that forms a first logical qubit (LQ) and a second set of PQs that forms a second LQ, is disclosed. A first subset of the first set of PQs is entangled with a second subset of the second set of PQs, forming a first set of entangled qubit-pairs. The entangled qubit-pairs are distributed across the first subset of PQs and the second subset of PQs. A fused LQ is formed that includes the first LQ, the second LQ is formed, and a set of fused stabilizers that spans the first LQ and the second LQ. The entangled qubit-pairs are employed as fused-measure qubits for the set of fused stabilizers. A quantum error correction (QEC) code is implemented on the fused LQ. The QEC code employs the fused stabilizers.