Present-day quantum processors are open systems in which dissipation and decoherence degrade the information carried by a quantum state as it propagates through a circuit. We study this degradation in dissipative random quantum circuits, modeling each two-qubit gate as a diluted unitary that interpolates between the intended unitary operation and a random dissipative quantum channel. Using the fidelity between the ideal and noisy output states as a diagnostic, we show that sufficiently random unitary gates or dissipative Kraus operators lead to a universal decay of the average fidelity. This decay is determined only by the dissipation strength, system size, and circuit depth, while microscopic details of the gates and noise, including the Kraus rank, appear only in subleading corrections to higher moments. We derive a closed-form expression for the average fidelity in terms of three physically meaningful error parameters, dissipation strength, coherent two-qubit gate-error strength, and connectivity-error probability. Finally, we identify the cases when dissipative effects can be reproduced by an unitary-noise model and when dissipation-induced decoherence remains distinguishable from coherent noise at the level of the average fidelity.
Simulating open quantum systems reveals how environmental coupling shapes relaxation, excitation transport, and the dynamics of quantum correlations. On quantum hardware, dissipative channels add operations and might seem to increase cost. However, we show that a broad class of Pauli noise, including depolarization, ca...
Armando Angrisani, Ricard Puig, Y. Teng et al.· 0 citations
Numerically study the tradeoff between depolarizing noise, entanglement as quantified by the bipartite negativity measure, and HOP in quantum volume circuits and highlight that under depolarizing noise, due to finite system size effects heavy output probabilities can be greater than $0.5$ while the bipartite negativity...
A "0-n"Fock qubit architecture that maintains the noise bias by encoding information in the ground state and n-th excited state of a nonlinear multi-level system, such as a transmon is proposed.
Su Direkci, Simon Lieu, K. Noh et al.· 0 citations
A quantum many-body system coupled to an environment relaxes to a nonequilibrium steady state that can sustain order with no equilibrium counterpart. Computing such steady states is harder than closed-system dynamics as the density matrix problem squares the Hilbert-space dimension, and no free energy selects the stead...
João C. Getelina, Andrew A. Cox, Md. Asaduzzaman et al.· 1 citation
Adding noise can make a random quantum circuit look faster without making its unitary dynamics more random. This distinction is especially relevant in modular processors, where local gates randomize each core and scarce inter-core communication must spread that randomness across the full device. In this paper, we study...
Hybrid quantum systems that integrate complementary advantages of different physical platforms provide a new pathway toward large-scale, fault-tolerant quantum information processing. In this work, we theoretically investigate a hybrid system consisting of a Rydberg atom, a piezoelectric nanomechanical resonator, and a...
