Observation of entanglement negativity transition of pseudo-random mixed states

Abstract

Multipartite entanglement is a key resource for quantum computation. It is expected theoretically that entanglement transition may happen for multipartite random quantum states, however, which is still absent experimentally. Here, we report the observation of entanglement transition quantified by negativity using a fully connected 20-qubit superconducting processor. We implement multi-layer pseudo-random circuits to generate pseudo-random pure states of 7 to 15 qubits. Then, we investigate negativity spectra of reduced density matrices obtained by quantum state tomography for 6 qubits.Three different phases can be identified by calculating logarithmic negativities based on the negativity spectra. We observe the phase transitions by changing the sizes of environment and subsystems. The randomness of our circuits can be also characterized by quantifying the distance between the distribution of output bit-string probabilities and Porter-Thomas distribution. Our simulator provides a powerful tool to generate random states and understand the entanglement structure for multipartite quantum systems.

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• Hilbert Space Fragmentation in Open Quantum Systems
• Phantom relaxation rate of the average purity evolution in random circuits due to Jordan non-Hermitian skin effect and magic sums
• Enhancing quantum state tomography via resource-efficient attention-based neural networks
• Entanglement phase diagrams from partial transpose moments
• Observation of multiple steady states with engineered dissipation
• Experimental Extraction of Coherent Ergotropy and Its Energetic Cost in a Superconducting Qubit
• Quantum synchronization in one-dimensional topological systems
• Tight upper bound for the maximal expectation value of the $N$-partite generalized Svetlichny operator
• Markov Gap and Bound Entanglement in Haar Random State
• Entanglement transition in a cluster spin chain coupled with free spins