Experimental construction of a W-superposition state and its equivalence to the GHZ state under local filtration

Abstract

We experimentally construct a novel three-qubit entangled W-superposition ($\mathrm{W}\bar{\mathrm{W}}$) state on an NMR quantum information processor. We give a measurement-based filtration protocol for the invertible local operation (ILO) that converts the $\mathrm{W}\bar{\mathrm{W}}$ state to the GHZ state, using a register of three ancilla qubits. Further we implement an experimental protocol to reconstruct full information about the three-party $\mathrm{W}\bar{\mathrm{W}}$ state using only two-party reduced density matrices. An intriguing fact unearthed recently is that the $\mathrm{W}\bar{\mathrm{W}}$ state which is equivalent to the GHZ state under ILO, is in fact reconstructible from its two-party reduced density matrices, unlike the GHZ state. We hence demonstrate that although the $\mathrm{W}\bar{\mathrm{W}}$ state is interconvertible with the GHZ state, it stores entanglement very differently.

7 pages Revtex4-1, Six eps figures

References in corpus (7)

• Entanglement detection
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• Evolution of tripartite entangled states in a decohering environment and their experimental protection using dynamical decoupling
• Constructing valid density matrices on an NMR quantum information processor via maximum likelihood estimation
• Dicke-state preparation through global transverse control of Ising-coupled qubits
• Experimental Classification of Entanglement in Arbitrary Three-Qubit States on an NMR Quantum Information Processor
• Scalable generation and detection of on-demand W states in nanophotonic circuits
• Efficient experimental design of high-fidelity three-qubit quantum gates via genetic programming
• Entanglement detection on an NMR quantum information processor using random local measurements
• Remote preparation of $W$ states from imperfect bipartite sources
• Experimentally identifying the entanglement class of pure tripartite states
• Classification and measurement of multipartite entanglement by reconstruction of correlation tensors on an NMR quantum processor
• Experimental Detection of Qubit-Ququart Pseudo-Bound Entanglement using Three Nuclear Spins
• State-independent robust heat-bath algorithmic cooling of nuclear spins