Abstract
The decoherence effects experienced by the qubits of a quantum processor are generally characterized using the amplitude damping time (T1) and the dephasing time (T2). Quantum channel models that exist at the time of writing assume that these parameters are fixed and invariant. However, recent experimental studies have shown that they exhibit a time-varying (TV) behaviour. These time-dependant fluctuations of T1 and T2, which become even more pronounced in the case of superconducting qubits, imply that conventional static quantum channel models do not capture the noise dynamics experienced by realistic qubits with sufficient precision. In this article, we study how the fluctuations of T1 and T2 can be included in quantum channel models. We propose the idea of time-varying quantum channel (TVQC) models, and we show how they provide a more realistic portrayal of decoherence effects than static models in some instances. We also discuss the divergence that exists between TVQCs and their static counterparts by means of a metric known as the diamond norm. In many circumstances this divergence can be significant, which indicates that the time-dependent nature of decoherence must be considered, in order to construct models that capture the real nature of quantum devices.
Highlights
Quantum error correction (QEC) is considered to be an essential building block in the endeavor of the scientific community to construct fully operational devices capable of conveying the advantages that quantum technology heralds
The quantum information community has gone to extraordinary lengths to construct quantum error correction codes (QECCs) that are capable of efficiently reversing the deleterious effects that quantum information experiences due to the interaction between qubits and their surrounding environment
This has led to the design of several promising families of QECCs, such as quantum Reed-Muller codes[1], quantum low-density parity-check (QLDPC) codes[2], quantum low-density generator matrix codes[3,4,5], quantum convolutional codes[6], quantum turbo codes (QTCs)[7,8,9,10,11], and quantum topological codes[12,13]
Summary
Quantum error correction (QEC) is considered to be an essential building block in the endeavor of the scientific community to construct fully operational devices capable of conveying the advantages that quantum technology heralds. The value of these error correction strategies, commonly known as quantum error correction codes (QECCs), lies in the fact that they protect quantum information from decoherence, a phenomenon to which quantum information is so sensitive that quantum computation is essentially unfeasible in the absence of error correction schemes. The quantum information community has gone to extraordinary lengths to construct QECCs that are capable of efficiently reversing the deleterious effects that quantum information experiences due to the interaction between qubits and their surrounding environment. We focus on error correction based on two-level physical constructions, and all the discussions refer to this specific approach to QECC
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