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An example of a transfer protocol in which our requirements are violated. The left panel displays the graph layout and the time-dependence of the couplings connected to p 1 and p 2. Because p 2 is unable to disconnect while preserving spins compatibility, there is a possibility that the relevant energy gap closes, which we indeed find here. As a result, the transfer error does not asymptotically decay to 0 as a function of T .
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Transporting quantum information is an important prerequisite for quantum computers. We study how this can be done in Heisenberg-coupled spin networks using adiabatic control over the coupling strengths. We find that qudits can be transferred and entangled pairs can be created between distant sites of bipartite graphs with a certain balance between...
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Context 1
... minimal example of a transfer protocol that does not match our requirements is displayed in Fig. 7. The bottom-left panel shows a graph in which p 1 can disconnect while leaving all other components in g = 0, but p 2 cannot. Choosing spin-1/2 particles (s j = s = 1/2) and the same time-dependent functions f and g for the couplings incident to p 1 and p 2 as before (Eq. 6), The left panel displays the graph layout and the ...
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A variety of pulse sequences have been described for converting nuclear spin magnetisation into long-lived singlet order for nuclear spin-1/2 pairs. Existing sequences operate well in two extreme parameter regimes. The magnetisation-to-singlet (M2S) pulse sequence performs a robust conversion of nuclear spin magnetisation into singlet order in the...
Citations
... Another new application is in a delayed transfer scheme, previously addressed in Ref. [37]. The sender a can initialize the system into the dark state |z and leave it at that, such that any party in P can retrieve the quantum state, at any time they like. ...
Adiabatic passage techniques, used to drive a system from one quantum state into another, find widespread application in physics and chemistry. We focus on the techniques called STImulated Raman Adiabatic Passage (STIRAP) and Coherent Tunnelling by Adiabatic Passage (CTAP), which employ a unique zero-energy eigenstate to transfer amplitude between ends of a linear chain. We find that many more general physical systems can use the same protocol, namely those with a (semi-)bipartite interaction graph which allows a perfect matching both when the sender is removed and when the receiver is removed. Many of the favorable stability properties of STIRAP/CTAP are inherited. We numerically test transfer between the leaves of a tree, and find surprisingly accurate transfer, especially when straddling is used. Our results open up new possibilities for coherent control and quantum state transfer in more general systems, and show that conventional STIRAP/CTAP is resilient to a large class of perturbations.
Adiabatic passage techniques, used to drive a system from one quantum state into another, find widespread applications in physics and chemistry. We focus on techniques to spatially transport a quantum amplitude over a strongly coupled system, such as STImulated Raman Adiabatic Passage (STIRAP) and Coherent Tunneling by Adiabatic Passage (CTAP). Previous results were shown to work on certain graphs, such as linear chains, square and triangular lattices, and branched chains. We prove that similar protocols work much more generally in a large class of (semi-)bipartite graphs. In particular, under random couplings, adiabatic transfer is possible on graphs that admit a perfect matching both when the sender is removed and when the receiver is removed. Many of the favorable stability properties of STIRAP/CTAP are inherited, and our results readily apply to transfer between multiple potential senders and receivers. We numerically test transfer between the leaves of a tree and find surprisingly accurate transfer, especially when straddling is used. Our results may find applications in short-distance communication between multiple quantum computers and open up a new question in graph theory about the spectral gap around the value 0.
Simulation of materials by using quantum processors is envisioned to be a major direction of development in quantum information science. Here, the mathematical analogies between a triangular spin lattice with Dzyaloshinskii–Moriya coupling on one edge and a three‐level system driven by three fields in a loop configuration are exploited to emulate spin‐transport effects. It is shown that the spin transport efficiency, seen in the three‐level system as population transfer, is enhanced when the conditions for superadiabaticity are satisfied. It is demonstrated experimentally that phenomena characteristic to spin lattices due to gauge invariance, non‐reciprocity, and broken time‐reversal symmetry can be reproduced in the three‐level system.
