Experimental construction of aWsuperposition state and its equivalence to the Greenberger-Horne-Zeilinger state under local filtration

Abstract

We experimentally construct a novel three-qubit entangled W-superposition (WW) state on an NMR quantum information processor. We give a measurement-based filtration protocol for the invertible local operation (ILO) that converts the WW 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 WW state using only two-party reduced density matrices. An intriguing fact unearthed recently is that the WW 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 WW state is interconvertible with the GHZ state, it stores entanglement very differently.

Experimentally identifying the entanglement class of pure tripartite states

“…5 for a desired duration was used to achieve non-local unitary operations. π 2 spin selective pulses for 1 H, 19 F and 13 C in the current study were 9.40 µs at 18.14 W power level, 22.50 µs at a power level of 42.27 W and 16.00 µs at a power level of 179.47 W, respectively.…”

“…Entangled states have been physically realized in superconducting phase qubits [11], nitrogen-vacancy defect centers [12], nuclear spin qubits [13], quantum dots [14] and trapped-ion [15] quantum computing hardwares. Entanglement creation and detection has been demonstrated in NMR [16][17][18][19][20] and pseudo-bound entanglement was detected using a three-qubit system [21]. There are several measures to quantify and detect the entanglement [2,22].…”

Experimental detection of qubit-ququart pseudo-bound entanglement using three nuclear spins

“…Several experimental efforts in this direction have tried to reduce the resources required to detect entanglement and have devised methods based on entanglement witnesses and positive maps to interrogate the presence of entanglement [18][19][20][21][22]. A range of experiments have been carried out to create and detect novel entangled states [23][24][25][26][27][28][29][30].…”

Experimental classification of entanglement in arbitrary three-qubit pure states on an NMR quantum information processor

“…Experimentally, entanglement has been created in various physical systems including nitrogen-vacancy defect centers [11], trapped-ion quantum computers [12], superconducting phase qubits [13] nuclear spin qubits [14] and quantum dots [15]. Bound entanglement was created and detected using three nuclear spins [16] and there have been several efforts to create and detect three-qubit entanglement using NMR [17][18][19][20][21]. Witness based entanglement detection protocols have been implemented experimentally in quantum optics [22] and NMR [23].…”