dorsal/arxiv
View SchemaFungible dynamics: there are only two types of entangling multiple-qubit interactions
| Authors | Michael J. Bremner, Jennifer L. Dodd, Michael A. Nielsen, Dave Bacon |
|---|---|
| Categories | |
| ArXiv ID | quant-ph/0307148 |
| URL | https://arxiv.org/abs/quant-ph/0307148 |
| DOI | 10.1103/PhysRevA.69.012313 |
| Journal | Phys. Rev. A 69 (1): Art. No. 012313 (2004) |
Abstract
What interactions are sufficient to simulate arbitrary quantum dynamics in a composite quantum system? It has been shown that all two-body Hamiltonian evolutions can be simulated using \emph{any} fixed two-body entangling $n$-qubit Hamiltonian and fast local unitaries. By \emph{entangling} we mean that every qubit is coupled to every other qubit, if not directly, then indirectly via intermediate qubits. We extend this study to the case where interactions may involve more than two qubits at a time. We find necessary and sufficient conditions for an arbitrary $n$-qubit Hamiltonian to be \emph{dynamically universal}, that is, able to simulate any other Hamiltonian acting on $n$ qubits, possibly in an inefficient manner. We prove that an entangling Hamiltonian is dynamically universal if and only if it contains at least one coupling term involving an \emph{even} number of interacting qubits. For \emph{odd} entangling Hamiltonians, i.e., Hamiltonians with couplings that involve only an odd number of qubits, we prove that dynamic universality is possible on an encoded set of $n-1$ logical qubits. We further prove that an odd entangling Hamiltonian can simulate any other odd Hamiltonian and classify the algebras that such Hamiltonians generate. Thus, our results show that up to local unitary operations, there are only two fundamentally different types of entangling Hamiltonian on $n$ qubits. We also demonstrate that, provided the number of qubits directly coupled by the Hamiltonian is bounded above by a constant, our techniques can be made efficient.
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"abstract": "What interactions are sufficient to simulate arbitrary quantum dynamics in a\ncomposite quantum system? It has been shown that all two-body Hamiltonian\nevolutions can be simulated using \\emph{any} fixed two-body entangling\n$n$-qubit Hamiltonian and fast local unitaries. By \\emph{entangling} we mean\nthat every qubit is coupled to every other qubit, if not directly, then\nindirectly via intermediate qubits. We extend this study to the case where\ninteractions may involve more than two qubits at a time. We find necessary and\nsufficient conditions for an arbitrary $n$-qubit Hamiltonian to be\n\\emph{dynamically universal}, that is, able to simulate any other Hamiltonian\nacting on $n$ qubits, possibly in an inefficient manner. We prove that an\nentangling Hamiltonian is dynamically universal if and only if it contains at\nleast one coupling term involving an \\emph{even} number of interacting qubits.\nFor \\emph{odd} entangling Hamiltonians, i.e., Hamiltonians with couplings that\ninvolve only an odd number of qubits, we prove that dynamic universality is\npossible on an encoded set of $n-1$ logical qubits. We further prove that an\nodd entangling Hamiltonian can simulate any other odd Hamiltonian and classify\nthe algebras that such Hamiltonians generate. Thus, our results show that up to\nlocal unitary operations, there are only two fundamentally different types of\nentangling Hamiltonian on $n$ qubits. We also demonstrate that, provided the\nnumber of qubits directly coupled by the Hamiltonian is bounded above by a\nconstant, our techniques can be made efficient.",
"arxiv_id": "quant-ph/0307148",
"authors": [
"Michael J. Bremner",
"Jennifer L. Dodd",
"Michael A. Nielsen",
"Dave Bacon"
],
"categories": [
"quant-ph"
],
"doi": "10.1103/PhysRevA.69.012313",
"journal_ref": "Phys. Rev. A 69 (1): Art. No. 012313 (2004)",
"title": "Fungible dynamics: there are only two types of entangling multiple-qubit interactions",
"url": "https://arxiv.org/abs/quant-ph/0307148"
},
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