The disentanglement and decoherence in the three-qubit system are studied based on the model of reservoir of harmonic oscillators by solving the non-Markovian approximation master equation,in which they are caused by a pure dephasing process.The GHZ-class state,W-class state and WGHZ-class state are discussed in detail.In all cases,the time scales of the decoherence and disentanglement are obtained.For the initial GHZ-class state,the coherence and entanglement decay completely;for the initial W-class state,the decoherence and disentanglement do not occur;for the initial WGHZ-class state,the decoherence happens partly,and the entanglement varies with time firstly and then becomes a certain asymptotic value.The disentanglement and decoherence in the three-qubit system are studied based on the model of reservoir of harmonic oscillators by solving the non-Markovian approximation master equation,in which they are caused by a pure dephasing process.The GHZ-class state,W-class state and WGHZ-class state are discussed in detail.In all cases,the time scales of the decoherence and disentanglement are obtained.For the initial GHZ-class state,the coherence and entanglement decay completely;for the initial W-class state,the decoherence and disentanglement do not occur;for the initial WGHZ-class state,the decoherence happens partly,and the entanglement varies with time firstly and then becomes a certain asymptotic value.

ACTA PHOTONICA SINICAJan 1, 20080 citations

The disentangled-state in the two-photon Jaynes-Cumming model with a Kerr-like medium

Wei Wei, Guo Guang-Can

The pure-state dynamical evolution of the atomic as well as the field states in the two-photon Jaynes-Cumming model with a Kerr-like medium for the field initially in the coherent state is investigated under the high-field approximation ( ≫ 1). Analytic expressions of the disentanglement conditions and the relevant disentangled states are derived, which are closely related to Kerr nonlinear coupling constant. This study also reveals that the initial atomic excited state can be evolved into the atomic dipole squeezed state.The pure-state dynamical evolution of the atomic as well as the field states in the two-photon Jaynes-Cumming model with a Kerr-like medium for the field initially in the coherent state is investigated under the high-field approximation ( ≫ 1). Analytic expressions of the disentanglement conditions and the relevant disentangled states are derived, which are closely related to Kerr nonlinear coupling constant. This study also reveals that the initial atomic excited state can be evolved into the atomic dipole squeezed state.

Acta Physica Sinica (Overseas Edition)Oct 1, 19970 citations

Untangling Entanglement

ScienceFeb 5, 20040 citations

A quantum oracle separation between QMA(2) and QMA

John Bostanci, Sabee Grewal, Jonas Haferkamp +4 more

We find a quantum oracle relative to which $\mathsf{QMA} \neq \mathsf{QMA}(2)$ . As a consequence, we resolve the no-disentanglers conjecture of Watrous: for every $ε+δ<1$ , any $(ε,δ)$ -disentangler requires input size exponential in the number of output qubits. Our proof combines the unitarily invariant polynomial method of She and Yuen (ITCS '23) with a new construction based on the symmetric and antisymmetric subspace projectors, reducing the $\mathsf{QMA}$ lower bound to the approximate degree of $\mathrm{OR}$ .We find a quantum oracle relative to which $\mathsf{QMA} \neq \mathsf{QMA}(2)$. As a consequence, we resolve the no-disentanglers conjecture of Watrous: for every $ε+δ<1$, any $(ε,δ)$-disentangler requires input size exponential in the number of output qubits. Our proof combines the unitarily invariant polynomial method of She and Yuen (ITCS '23) with a new construction based on the symmetric and antisymmetric subspace projectors, reducing the $\mathsf{QMA}$ lower bound to the approximate degree of $\mathrm{OR}$.

quant-pharXiv:2609.02865Sep 3, 20260 citations

Untangling Entanglement

Peter Mark Ainsworth

Foundations of PhysicsJan 5, 20073 citations

We find a quantum oracle relative to which

\mathsf{QMA} \neq \mathsf{QMA}(2)

. As a consequence, we resolve the no-disentanglers conjecture of Watrous: for every

ε+δ<1

, any

(ε,δ)

-disentangler requires input size exponential in the number of output qubits. Our proof combines the unitarily invariant polynomial method of She and Yuen (ITCS '23) with a new construction based on the symmetric and antisymmetric subspace projectors, reducing the

\mathsf{QMA}

lower bound to the approximate degree of

\mathrm{OR}