Different measurements of the same environment can preserve the average quantum channel yet change the feedback strength needed to prepare a state ensemble. We establish this distinction for a multiqubit register under complete Pauli monitoring, targeting the uniform ensemble of real-amplitude pure states. With unit detection efficiency, public records, and bounded Hamiltonian feedback, fixed transverse noise requires a minimum peak strength proportional to $\epsilon^{-1}$ at distributional error $\epsilon$. Tangent noise instead admits a construction requiring only $O[\sqrt{\log(1/\epsilon)}]$. At fixed preparation time, we determine the optimum over all allowed feedback policies and derive a geometric lower bound beyond radial symmetry. The separation identifies the measurement realization as part of the control-resource specification for monitored ensemble preparation.
Efficient, deterministic, and high-fidelity preparation of large Fock states is essential for scaling bosonic quantum technologies and exploring quantum phenomena at large excitation energies. We introduce a deterministic one-parameter (D1p) protocol that maps Fock-state preparation in an infinite-dimensional Hilbert s...
We determine the ultimate information rate of a relaxing multilevel quantum sensor under unrestricted adaptive control and construct an explicit strategy that attains it. We consider sensing a weak field that couples the ground state to several excited states that decay back to the ground state, a setting that reduces...
Preparing logical codewords with a single round of noisy syndrome measurements can reduce the time overhead of fault-tolerant quantum computation. It remains unclear which structural properties of the code suffice to guarantee a threshold for single-shot state preparation. Here we prove that linear confinement suffices...
Yuan-Yuan Zhao, Yi-Zheng Yuan, Zhen Han et al.· 0 citations
It is confirmed that an ideal sequential and terminal measurement schedule delivers the same complete bit string distribution under matched causal operations, while normalized postselection can amplify perturbations inversely with prefix acceptance.
Bhvain Makwana, Kashyap Patel, Manjunath Joshi et al.· 0 citations
Single-qubit channels provide a controlled setting for comparing how different noise mechanisms change a quantum state. Using density matrices and Kraus operators, this paper compares bit-flip, phase-flip, depolarising, amplitudedamping, and phase-damping channels under the same set of input states and diagnostic metri...
Polina Kravchenko, Y. Darnapuk, G. Chuiko· International Conference on...· 0 citations
We study recoverable entanglement in a four-qubit cluster-state register whose two detector qubits couple to a scalar field. A local preparation phase leaves the initial reference--register entanglement and detector marginal unchanged, but controls protection under collective noise. At the optimal phase, a fixed decode...
Zhi-Ming Huang· 0 citations
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