Quantum 5, 441 (2021). https://doi.org/10.22331/q-2021-04-26-441 Similarly to quantum states, quantum operations can also be transformed by means of quantum superchannels, also known as process matrices. Quantum superchannels with multiple slots are deterministic transformations which take […]
Quantum 5, 440 (2021). https://doi.org/10.22331/q-2021-04-26-440 We present a method to detect quantum memory in a non-Markovian process. We call a process Markovian when the environment does not provide a memory that retains correlations across different […]
Quantum 5, 439 (2021). https://doi.org/10.22331/q-2021-04-26-439 The exchange of information between an open quantum system and its environment allows us to discriminate among different kinds of dynamics, in particular detecting memory effects to characterize non-Markovianity. Here, […]
Quantum 5, 438 (2021). https://doi.org/10.22331/q-2021-04-22-438 We introduce “fractalization”, a procedure by which spin models are extended to higher-dimensional “fractal” spin models. This allows us to interpret type-II fracton phases, fractal symmetry-protected topological phases, and more, […]
Quantum 5, 437 (2021). https://doi.org/10.22331/q-2021-04-20-437 The $p$-stage Quantum Approximate Optimization Algorithm (QAOA$_p$) is a promising approach for combinatorial optimization on noisy intermediate-scale quantum (NISQ) devices, but its theoretical behavior is not well understood beyond $p=1$. […]
Quantum 5, 436 (2021). https://doi.org/10.22331/q-2021-04-20-436 Suppose we want to implement a unitary $U$, for instance a circuit for some quantum algorithm. Suppose our actual implementation is a unitary $tilde{U}$, which we can only apply as […]
Quantum 5, 435 (2021). https://doi.org/10.22331/q-2021-04-20-435 We investigate the conditions under which an uncontrollable background processes may be harnessed by an agent to perform a task that would otherwise be impossible within their operational framework. This […]
Quantum 5, 434 (2021). https://doi.org/10.22331/q-2021-04-19-434 The hybrid quantum-classical algorithm is actively examined as a technique applicable even to intermediate-scale quantum computers. To execute this algorithm, the hardware efficient ansatz is often used, thanks to its […]
Quantum 5, 433 (2021). https://doi.org/10.22331/q-2021-04-15-433 We significantly reduce the cost of factoring integers and computing discrete logarithms in finite fields on a quantum computer by combining techniques from Shor 1994, Griffiths-Niu 1996, Zalka 2006, Fowler […]
Quantum 5, 432 (2021). https://doi.org/10.22331/q-2021-04-15-432 Hypergraph product codes are a class of constant-rate quantum low-density parity-check (LDPC) codes equipped with a linear-time decoder called small-set-flip (SSF). This decoder displays sub-optimal performance in practice and requires […]
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