Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userEntanglement generation between distant parties via disordered spin chains
125
0
0.0
(
0
)
Added by
Guilherme Martins Alves De Almeida
Publication date
2017
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We study the emergence of bipartite entanglement between a pair of spins weakly connected to the ends of a linear disordered $XY$ spin-1/2 channel. We analyze how their concurrence responds to structural and on-site fluctuations embodied by long-range spatially-correlated sequences. We show that the end-to-end entanglement is very robust against disorder and asymmetries in the channel provided that the degree of correlations are strong enough and both entangling parties are tuned accordingly. Our results offer further alternatives in the design of stable quantum communication protocols via imperfect channels.
rate research
Read More
Entanglement is a vital property of multipartite quantum systems, characterised by the inseparability of quantum states of objects regardless of their spatial separation. Generation of entanglement between increasingly macroscopic and disparate systems is an ongoing effort in quantum science which enables hybrid quantum networks, quantum-enhanced sensing, and probing the fundamental limits of quantum theory. The disparity of hybrid systems and the vulnerability of quantum correlations have thus far hampered the generation of macroscopic hybrid entanglement. Here we demonstrate, for the first time, generation of an entangled state between the motion of a macroscopic mechanical oscillator and a collective atomic spin oscillator, as witnessed by an Einstein-Podolsky-Rosen variance below the separability limit, $0.83 pm 0.02<1$. The mechanical oscillator is a millimeter-size dielectric membrane and the spin oscillator is an ensemble of $10^9$ atoms in a magnetic field. Light propagating through the two spatially separated systems generates entanglement due to the collective spin playing the role of an effective negative-mass reference frame and providing, under ideal circumstances, a backaction-free subspace; in the experiment, quantum backaction is suppressed by 4.6 dB. Our results pave the road towards measurement of motion beyond the standard quantum limits of sensitivity with applications in force, acceleration,and gravitational wave detection, as well as towards teleportation-based protocols in hybrid quantum networks.
Using an operational definition we quantify the entanglement, $E_P$, between two parties who share an arbitrary pure state of $N$ indistinguishable particles. We show that $E_P leq E_M$, where $E_M$ is the bipartite entanglement calculated from the mode-occupation representation. Unlike $E_M$, $E_P$ is {em super-additive}. For example, $E_P =0$ for any single-particle state, but the state $ket{1}ket{1}$, where both modes are split between the two parties, has $E_P = 1/2$. We discuss how this relates to quantum correlations between particles, for both fermions and bosons.
Quantum entanglement between distant qubits is an important feature of quantum networks. Distribution of entanglement over long distances can be enabled through coherently interfacing qubit pairs via photonic channels. Here, we report the realization of optically generated quantum entanglement between electron spin qubits confined in two distant semiconductor quantum dots. The protocol relies on spin-photon entanglement in the trionic $Lambda$-system and quantum erasure of the Raman-photon path. The measurement of a single Raman photon is used to project the spin qubits into a joint quantum state with an interferometrically stabilized and tunable relative phase. We report an average Bell-state fidelity for $|psi^{(+)}rangle$ and $|psi^{(-)}rangle$ states of $61.6pm2.3%$ and a record-high entanglement generation rate of 7.3 kHz between distant qubits.
We show how the entanglement of two atoms, trapped in distant separate cavities, can be generated with arbitrarily high probability of success. The scheme proposed employs sudden excitation of the atoms proving that the weakly driven condition is not necessary to obtain the success rate close to unity. The modified scheme works properly even if each cavity contains many atoms interacting with the cavity modes. We also show that our method is robust against the spontaneous atomic decay.
We propose a protocol for state transfer and entanglement generation between two distant spin qubits (sender and receiver) that have different energies. The two qubits are permanently coupled to a far off-resonant spin-chain, and the qubit of the sender is driven by an external field, which provides the energy required to bridge the energy gap between the sender and the receiver. State transfer and entanglement generation are achieved via virtual single-photon and multi-photon transitions to the eigenmodes of the channel.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
