Quantum separability

Is every promise problem verifiable by a quantum Merlin-Arthur protocol with two unentangled witnesses also verifiable by a protocol with a single arbitrary witness, that is, is \(\mathsf{QMA}(2) = \mathsf{QMA}\) in the standard, unrelativized setting?

• Quantum algorithm
• Computational complexity and computability
• Quantum separability

Must the composition of any two compatible PPT completely positive maps be entanglement breaking?

• Quantum Resource Theory
• Quantum Communication
• Quantum separability
• Quantum channel structure

Characterize the spectra of bipartite states that remain separable under every global unitary, and decide whether absolute separability equals absolute positivity under partial transpose in higher local dimensions.

• Quantum Resource Theory
• Quantum separability

Find a closed formula for the relative entropy of entanglement of every two-qubit density operator \(\rho\), including an explicit closest separable state.

• Quantum Resource Theory
• Entanglement measures
• Quantum separability
• Quantum relative entropy

What is the computational complexity of testing bipartite separability with a constant trace-distance promise gap?

• Quantum algorithm
• Quantum Resource Theory
• Quantum separability
• Computational complexity and computability