论文标题

减轻本地费米文编码中的错误

Mitigating Errors in Local Fermionic Encodings

论文作者

Bausch, Johannes, Cubitt, Toby, Derby, Charles, Klassen, Joel

论文摘要

费米子多体系统的量子模拟至关重要的是依赖于无法区分的费米的映射来区分Qubits。费米子植物空间的非本地结构需要编码,以将本地费米子操作员映射到非本地Qubit Operators,或者在远程纠缠的代码空间中编码费米子表示。在后一种情况下,编码的两个理想属性之间存在不可避免的权衡:本地费米子操作员的低权重表示和一个高距离代码空间。在这里,人们认为,尽管具有这种基本限制,但在局部费米子运营商中具有低重量表示的费米子编码仍然可以表现出缓解属性的错误,这些属性可以与高密码距离发挥的作用相似。特别是当无法检测到的误差对应于“自然”费米噪声时。我们明确说明了这一点,以说明两个费米子编码:Verstraete-Cirac编码,以及Derby和Klassen的并发作品中出现的编码。在这些编码的许多(但不是全部)中,可以检测到单量错误。但是,我们表明其余的未检测到的单量错误映射到局部,低重量的费米子相位噪声。我们认为,这种噪声对于费米子晶格模型是自然的。这表明,即使采用低重费用编码,也可以以与高距离代码相似的方式抑制错误率,前提是人们愿意在其模拟的费米子系统中接受模拟的自然费米噪声。

Quantum simulations of fermionic many-body systems crucially rely on mappings from indistinguishable fermions to distinguishable qubits. The non-local structure of fermionic Fock space necessitates encodings that either map local fermionic operators to non-local qubit operators, or encode the fermionic representation in a long-range entangled code space. In this latter case, there is an unavoidable trade-off between two desirable properties of the encoding: low weight representations of local fermionic operators, and a high distance code space. Here it is argued that despite this fundamental limitation, fermionic encodings with low-weight representations of local fermionic operators can still exhibit error mitigating properties which can serve a similar role to that played by high code distances. In particular when undetectable errors correspond to "natural" fermionic noise. We illustrate this point explicitly for two fermionic encodings: the Verstraete-Cirac encoding, and an encoding appearing in concurrent work by Derby and Klassen. In these encodings many, but not all, single-qubit errors can be detected. However we show that the remaining undetectable single-qubit errors map to local, low-weight fermionic phase noise. We argue that such noise is natural for fermionic lattice models. This suggests that even when employing low-weight fermionic encodings, error rates can be suppressed in a similar fashion to high distance codes, provided one is willing to accept simulated natural fermionic noise in their simulated fermionic system.

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