Gavin Brennen - Profile on Academia.edu (original) (raw)
Papers by Gavin Brennen
Physical Review Letters, Feb 21, 2020
We propose a physical realization of quantum cellular automata (QCA) using arrays of ultracold at... more We propose a physical realization of quantum cellular automata (QCA) using arrays of ultracold atoms excited to Rydberg states. The key ingredient is the use of programmable multifrequency couplings which generalize the Rydberg blockade and facilitation effects to a broader set of nonadditive, unitary and non-unitary (dissipative) conditional interactions. Focusing on a 1D array we define a set of elementary QCA rules that generate complex and varied quantum dynamical behavior. Finally we demonstrate theoretically that Rydberg QCA is ideally suited for variational quantum optimization protocols and quantum state engineering by finding parameters that generate highly entangled states as the steady state of the quantum dynamics.
APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts, May 1, 2003
Several authors have described the basic requirements essential to build a scalable quantum compu... more Several authors have described the basic requirements essential to build a scalable quantum computer. Because many physical implementation schemes for quantum computing rely on nearest neighbor interactions, there is a hidden quantum communication overhead to connect distant nodes of the computer. In this paper we propose a physical solution to this problem which, together with the key building blocks, provides a pathway to a scalable quantum architecture using nonlocal interactions. Our solution involves the concept of a quantum bus that acts as a refreshable entanglement resource to connect distant memory nodes providing an architectural concept for quantum computers analogous to the von Neumann architecture for classical computers.
Bulletin of the American Physical Society, Mar 16, 2010
Quantum logic gates with neutral atoms in an optical lattice
Technical Digest. Summaries of Papers Presented at the International Quantum Electronics Conference. Conference Edition. 1998 Technical Digest Series, Vol.7 (IEEE Cat. No.98CH36236)
Quantum logic gates require qubits that can interact strongly with each other and with external f... more Quantum logic gates require qubits that can interact strongly with each other and with external fields while minimizing unwanted coupling to the decohering environment. Neutral atoms trapped in a far-off resonance optical lattice satisfy these criteria. The adjustable parameters of the lattice (e.g., laser polarization, frequency, intensity) allow one to design interactions for which atoms interact strongly via dipole-dipole interactions
Entangling dipole-dipole interactions in optical lattices
Quantum Electronics and Laser Science Conference, 2001
Summary form only given. Controlled coherent interactions between pairs of neutral atoms can be d... more Summary form only given. Controlled coherent interactions between pairs of neutral atoms can be designed in tight micro-traps such as optical lattices which allow the creation of highly entangled multiparticle states. Such systems benefit from suppressed decoherence because neutrals couple weakly to the environment and the interactions are strictly pairwise. The main source of decoherence is spontaneous emission which can
Controlling atom-atom interactions in optical lattices
Quantum Electronics and Laser Science Conference, 1999
Optical lattices provide new opportunities to create entangled states of neutral atoms for quantu... more Optical lattices provide new opportunities to create entangled states of neutral atoms for quantum information processing. Such systems have some attractive features: decoherence is suppressed because neutrals couple weakly to the environment, and operations can be performed in parallel on a large ensemble of trapped atoms, thus offering avenues for scaling to many qubits. The main source of decoherence is
Quantum Logic Gates in Optical Lattices
Physical Review Letters, 1999
Entangling dipole-dipole interactions with neutral atoms in an optical lattice
A scalable quantum architecture using efficient non-local gates
Information transport in 1D quantum cellular automata
ABSTRACT
Designing spin lattice models with polar molecules: a route to topological order
The Schmidt decomposition is an important tool in the study of quantum systems especially for the... more The Schmidt decomposition is an important tool in the study of quantum systems especially for the quantification of the entanglement of pure states. However, the Schmidt decomposition is only unique for bipartite pure states, and some multipartite pure states. Here a generalized Schmidt decomposition is given for a class of mixed quantum states. It is shown that it shares some desirable properties with its pure-state counterpart, but lacks some properties which make the pure-state decomposition so important. Experimental methods for the identification of this class of mixed states are provided and some examples are discussed which show the utility of this description.
Sideband Cooling, State Control, And Quantum Logic In Optical Lattices
An Australian strategy for the quantum revolution
International Cyber Policy Centre, May 13, 2021
Physical Review Letters, Mar 20, 2020
We discuss a technique to strongly couple a single target quantum emitter to a cavity mode, which... more We discuss a technique to strongly couple a single target quantum emitter to a cavity mode, which is enabled by virtual excitations of a nearby mesoscopic ensemble of emitters. A collective coupling of the latter to both the cavity and the target emitter induces strong photon non-linearities in addition to polariton formation, in contrast to common schemes for ensemble strong coupling. We demonstrate that strong coupling at the level of a single emitter can be engineered via coherent and dissipative dipolar interactions with the ensemble, and provide realistic parameters for a possible implementation with SiV − defects in diamond. Our scheme can find applications, amongst others, in quantum information processing or in the field of cavity-assisted quantum chemistry.
An Australian strategy for the quantum revolution
Input-output theory for chiral Majorana fermions
Bulletin of the American Physical Society, Mar 6, 2018
arXiv (Cornell University), Apr 12, 2022
The development of high-resolution, large-baseline optical interferometers would revolutionize as... more The development of high-resolution, large-baseline optical interferometers would revolutionize astronomical imaging. However, classical techniques are hindered by physical limitations including loss, noise, and the fact that the received light is generally quantum in nature. We show how to overcome these issues using quantum communication techniques. We present a general framework for using quantum error correction codes for protecting and imaging starlight received at distant telescope sites. In our scheme, the quantum state of light is coherently captured into a non-radiative atomic state via Stimulated Raman Adiabatic Passage, which is then imprinted into a quantum error correction code. The code protects the signal during subsequent potentially noisy operations necessary to extract the image parameters. We show that even a small quantum error correction code can offer significant protection against noise. For large codes, we find noise thresholds below which the information can be preserved. Our scheme represents an application for near-term quantum devices that can increase imaging resolution beyond what is feasible using classical techniques.
arXiv (Cornell University), Apr 21, 2022
The information flow in a quantum system is a fundamental feature of its dynamics. An important c... more The information flow in a quantum system is a fundamental feature of its dynamics. An important class of dynamics are quantum cellular automata (QCA), systems with discrete updates invariant in time and space, for which an index theory has been proposed for the quantification of the net flow of quantum information across a boundary. While the index is rigid in the sense of begin invariant under finite-depth local circuits, it is not defined when the system is coupled to an environment, i.e. for non-unitary time evolution of open quantum systems. We propose a new measure of information flow for non-unitary QCA denoted the information current which is not rigid, but can be computed locally based on the matrix-product operator representation of the map.
Entangling Dipole-Dlpole Interactions In
Physical Review Letters, Feb 21, 2020
We propose a physical realization of quantum cellular automata (QCA) using arrays of ultracold at... more We propose a physical realization of quantum cellular automata (QCA) using arrays of ultracold atoms excited to Rydberg states. The key ingredient is the use of programmable multifrequency couplings which generalize the Rydberg blockade and facilitation effects to a broader set of nonadditive, unitary and non-unitary (dissipative) conditional interactions. Focusing on a 1D array we define a set of elementary QCA rules that generate complex and varied quantum dynamical behavior. Finally we demonstrate theoretically that Rydberg QCA is ideally suited for variational quantum optimization protocols and quantum state engineering by finding parameters that generate highly entangled states as the steady state of the quantum dynamics.
APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts, May 1, 2003
Several authors have described the basic requirements essential to build a scalable quantum compu... more Several authors have described the basic requirements essential to build a scalable quantum computer. Because many physical implementation schemes for quantum computing rely on nearest neighbor interactions, there is a hidden quantum communication overhead to connect distant nodes of the computer. In this paper we propose a physical solution to this problem which, together with the key building blocks, provides a pathway to a scalable quantum architecture using nonlocal interactions. Our solution involves the concept of a quantum bus that acts as a refreshable entanglement resource to connect distant memory nodes providing an architectural concept for quantum computers analogous to the von Neumann architecture for classical computers.
Bulletin of the American Physical Society, Mar 16, 2010
Quantum logic gates with neutral atoms in an optical lattice
Technical Digest. Summaries of Papers Presented at the International Quantum Electronics Conference. Conference Edition. 1998 Technical Digest Series, Vol.7 (IEEE Cat. No.98CH36236)
Quantum logic gates require qubits that can interact strongly with each other and with external f... more Quantum logic gates require qubits that can interact strongly with each other and with external fields while minimizing unwanted coupling to the decohering environment. Neutral atoms trapped in a far-off resonance optical lattice satisfy these criteria. The adjustable parameters of the lattice (e.g., laser polarization, frequency, intensity) allow one to design interactions for which atoms interact strongly via dipole-dipole interactions
Entangling dipole-dipole interactions in optical lattices
Quantum Electronics and Laser Science Conference, 2001
Summary form only given. Controlled coherent interactions between pairs of neutral atoms can be d... more Summary form only given. Controlled coherent interactions between pairs of neutral atoms can be designed in tight micro-traps such as optical lattices which allow the creation of highly entangled multiparticle states. Such systems benefit from suppressed decoherence because neutrals couple weakly to the environment and the interactions are strictly pairwise. The main source of decoherence is spontaneous emission which can
Controlling atom-atom interactions in optical lattices
Quantum Electronics and Laser Science Conference, 1999
Optical lattices provide new opportunities to create entangled states of neutral atoms for quantu... more Optical lattices provide new opportunities to create entangled states of neutral atoms for quantum information processing. Such systems have some attractive features: decoherence is suppressed because neutrals couple weakly to the environment, and operations can be performed in parallel on a large ensemble of trapped atoms, thus offering avenues for scaling to many qubits. The main source of decoherence is
Quantum Logic Gates in Optical Lattices
Physical Review Letters, 1999
Entangling dipole-dipole interactions with neutral atoms in an optical lattice
A scalable quantum architecture using efficient non-local gates
Information transport in 1D quantum cellular automata
ABSTRACT
Designing spin lattice models with polar molecules: a route to topological order
The Schmidt decomposition is an important tool in the study of quantum systems especially for the... more The Schmidt decomposition is an important tool in the study of quantum systems especially for the quantification of the entanglement of pure states. However, the Schmidt decomposition is only unique for bipartite pure states, and some multipartite pure states. Here a generalized Schmidt decomposition is given for a class of mixed quantum states. It is shown that it shares some desirable properties with its pure-state counterpart, but lacks some properties which make the pure-state decomposition so important. Experimental methods for the identification of this class of mixed states are provided and some examples are discussed which show the utility of this description.
Sideband Cooling, State Control, And Quantum Logic In Optical Lattices
An Australian strategy for the quantum revolution
International Cyber Policy Centre, May 13, 2021
Physical Review Letters, Mar 20, 2020
We discuss a technique to strongly couple a single target quantum emitter to a cavity mode, which... more We discuss a technique to strongly couple a single target quantum emitter to a cavity mode, which is enabled by virtual excitations of a nearby mesoscopic ensemble of emitters. A collective coupling of the latter to both the cavity and the target emitter induces strong photon non-linearities in addition to polariton formation, in contrast to common schemes for ensemble strong coupling. We demonstrate that strong coupling at the level of a single emitter can be engineered via coherent and dissipative dipolar interactions with the ensemble, and provide realistic parameters for a possible implementation with SiV − defects in diamond. Our scheme can find applications, amongst others, in quantum information processing or in the field of cavity-assisted quantum chemistry.
An Australian strategy for the quantum revolution
Input-output theory for chiral Majorana fermions
Bulletin of the American Physical Society, Mar 6, 2018
arXiv (Cornell University), Apr 12, 2022
The development of high-resolution, large-baseline optical interferometers would revolutionize as... more The development of high-resolution, large-baseline optical interferometers would revolutionize astronomical imaging. However, classical techniques are hindered by physical limitations including loss, noise, and the fact that the received light is generally quantum in nature. We show how to overcome these issues using quantum communication techniques. We present a general framework for using quantum error correction codes for protecting and imaging starlight received at distant telescope sites. In our scheme, the quantum state of light is coherently captured into a non-radiative atomic state via Stimulated Raman Adiabatic Passage, which is then imprinted into a quantum error correction code. The code protects the signal during subsequent potentially noisy operations necessary to extract the image parameters. We show that even a small quantum error correction code can offer significant protection against noise. For large codes, we find noise thresholds below which the information can be preserved. Our scheme represents an application for near-term quantum devices that can increase imaging resolution beyond what is feasible using classical techniques.
arXiv (Cornell University), Apr 21, 2022
The information flow in a quantum system is a fundamental feature of its dynamics. An important c... more The information flow in a quantum system is a fundamental feature of its dynamics. An important class of dynamics are quantum cellular automata (QCA), systems with discrete updates invariant in time and space, for which an index theory has been proposed for the quantification of the net flow of quantum information across a boundary. While the index is rigid in the sense of begin invariant under finite-depth local circuits, it is not defined when the system is coupled to an environment, i.e. for non-unitary time evolution of open quantum systems. We propose a new measure of information flow for non-unitary QCA denoted the information current which is not rigid, but can be computed locally based on the matrix-product operator representation of the map.
Entangling Dipole-Dlpole Interactions In