The Experts below are selected from a list of 1419 Experts worldwide ranked by ideXlab platform
Klaus Mølmer - One of the best experts on this subject based on the ideXlab platform.
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Geometric phases in open tripod systems
Physical Review A, 2008Co-Authors: Ditte Moller, Lars Bojer Madsen, Klaus MølmerAbstract:We first consider stimulated Raman adiabatic passages in a closed four-level tripod system. In this case, the adiabatic eigenstates of the system acquire real geometric phases. When the system is open and subject to decoherence they acquire complex geometric phases that we determine by a Monte Carlo wave function approach. We calculate the geometric phases and the state evolution in the closed as well as in the open system cases and describe the deviation between these in terms of the phases acquired. When the system is closed, the adiabatic evolution implements a Hadamard Gate. The open system implements an imperfect Gate and hence has a fidelity below unity. We express this fidelity in terms of the acquired geometric phases.
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Geometric phase Gates based on stimulated Raman adiabatic passage in tripod systems
Physical Review A, 2007Co-Authors: Ditte Moller, Lars Bojer Madsen, Klaus MølmerAbstract:We consider stimulated Raman adiabatic passage (STIRAP) processes in tripod systems and show how to generate purely geometric phase changes of the quantum states involved. The geometric phases are controlled by three laser fields where pulse shapes, relative field strength, and phases can be controlled. We present a robust set of universal Gates for quantum computing based on these geometric phases: a one-qubit phase Gate, a Hadamard Gate, and a two-qubit phase Gate.
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Geometric phase Gates based on stimulated Raman adiabatic passage in tripod systems
Physical Review A, 2007Co-Authors: Ditte Moller, Lars Bojer Madsen, Klaus MølmerAbstract:We consider stimulated Raman adiabatic passage (STIRAP) processes in tripod systems and show how to generate purely geometric phase changes of the quantum states involved. The geometric phases are controlled by three laser fields where pulse shapes, relative field strength and phases can be controlled. We present a robust set of universal Gates for quantum computing based on these geometric phases: a one-qubit phase Gate, a Hadamard Gate and a two-qubit phase Gate.Comment: 6 pages, 3 figure
Ofer Biham - One of the best experts on this subject based on the ideXlab platform.
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Effect of unitary noise on Grover's quantum search algorithm
Physical Review A, 2003Co-Authors: Daniel Shapira, Shay Mozes, Ofer BihamAbstract:The effect of unitary noise on the performance of Grover's quantum search algorithm is studied. This type of noise may result from tiny fluctuations and drift in the parameters of the (quantum) components performing the computation. The resulting operations are still unitary, but not precisely those assumed in the design of the algorithm. Here we focus on the effect of such noise in the Hadamard Gate W, which is an essential component in each iteration of the quantum search process. To this end W is replaced by a noisy Hadamard Gate U. The parameters of U at each iteration are taken from an arbitrary probability distribution (e.g., a Gaussian distribution) and are characterized by their statistical moments around the parameters of W. For simplicity, we assume that the noise is unbiased and isotropic, namely, all noise variables in the parametrization we use have zero average and the same standard deviation {epsilon}. The noise terms at different calls to U are assumed to be uncorrelated. For a search space of size N=2{sup n} (where n is the number of qubits used to span this space) it is found that as long as {epsilon}
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effect of unitary noise on grover s quantum search algorithm
Physical Review A, 2003Co-Authors: Daniel Shapira, Shay Mozes, Ofer BihamAbstract:The effect of unitary noise on the performance of Grover's quantum search algorithm is studied. This type of noise may result from tiny fluctuations and drift in the parameters of the (quantum) components performing the computation. The resulting operations are still unitary, but not precisely those assumed in the design of the algorithm. Here we focus on the effect of such noise in the Hadamard Gate W, which is an essential component in each iteration of the quantum search process. To this end W is replaced by a noisy Hadamard Gate U. The parameters of U at each iteration are taken from an arbitrary probability distribution (e.g., a Gaussian distribution) and are characterized by their statistical moments around the parameters of W. For simplicity, we assume that the noise is unbiased and isotropic, namely, all noise variables in the parametrization we use have zero average and the same standard deviation {epsilon}. The noise terms at different calls to U are assumed to be uncorrelated. For a search space of size N=2{sup n} (where n is the number of qubits used to span this space) it is found that as long as {epsilon}
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Effect of unitary noise on Grover's quantum search algorithm
Physical Review A, 2003Co-Authors: Daniel Shapira, Shay Mozes, Ofer BihamAbstract:The effect of unitary noise on the performance of Grover's quantum search algorithm is studied. This type of noise may result from tiny fluctuations and drift in the parameters of the (quantum) components performing the computation. The resulting operations are still unitary, but not precisely those assumed in the design of the algorithm. Here we focus on the effect of such noise in the Hadamard Gate $W$, which is an essential component in each iteration of the quantum search process. To this end $W$ is replaced by a noisy Hadamard Gate $U$. The parameters of $U$ at each iteration are taken from an arbitrary probability distribution (e.g. Gaussian distribution) and are characterized by their statistical moments around the parameters of $W$. For simplicity we assume that the noise is unbiased and isotropic, namely all noise variables in the parametrization we use have zero average and the same standard deviation $\epsilon$. The noise terms at different calls to $U$ are assumed to be uncorrelated. For a search space of size $N=2^n$ (where $n$ is the number of qubits used to span this space) it is found that as long as $\epsilon < O(n^{-{1/2}} N^{-{1/4}})$, the algorithm maintains significant efficiency, while above this noise level its operation is hampered completely. It is also found that below this noise threshold, when the search fails, it is likely to provide a state that differs from the marked state by only a few bits. This feature can be used to search for the marked state by a classical post-processing, even if the quantum search has failed, thus improving the success rate of the search process
Ditte Moller - One of the best experts on this subject based on the ideXlab platform.
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Geometric phases in open tripod systems
Physical Review A, 2008Co-Authors: Ditte Moller, Lars Bojer Madsen, Klaus MølmerAbstract:We first consider stimulated Raman adiabatic passages in a closed four-level tripod system. In this case, the adiabatic eigenstates of the system acquire real geometric phases. When the system is open and subject to decoherence they acquire complex geometric phases that we determine by a Monte Carlo wave function approach. We calculate the geometric phases and the state evolution in the closed as well as in the open system cases and describe the deviation between these in terms of the phases acquired. When the system is closed, the adiabatic evolution implements a Hadamard Gate. The open system implements an imperfect Gate and hence has a fidelity below unity. We express this fidelity in terms of the acquired geometric phases.
-
Geometric phase Gates based on stimulated Raman adiabatic passage in tripod systems
Physical Review A, 2007Co-Authors: Ditte Moller, Lars Bojer Madsen, Klaus MølmerAbstract:We consider stimulated Raman adiabatic passage (STIRAP) processes in tripod systems and show how to generate purely geometric phase changes of the quantum states involved. The geometric phases are controlled by three laser fields where pulse shapes, relative field strength, and phases can be controlled. We present a robust set of universal Gates for quantum computing based on these geometric phases: a one-qubit phase Gate, a Hadamard Gate, and a two-qubit phase Gate.
-
Geometric phase Gates based on stimulated Raman adiabatic passage in tripod systems
Physical Review A, 2007Co-Authors: Ditte Moller, Lars Bojer Madsen, Klaus MølmerAbstract:We consider stimulated Raman adiabatic passage (STIRAP) processes in tripod systems and show how to generate purely geometric phase changes of the quantum states involved. The geometric phases are controlled by three laser fields where pulse shapes, relative field strength and phases can be controlled. We present a robust set of universal Gates for quantum computing based on these geometric phases: a one-qubit phase Gate, a Hadamard Gate and a two-qubit phase Gate.Comment: 6 pages, 3 figure
Daniel Shapira - One of the best experts on this subject based on the ideXlab platform.
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Effect of unitary noise on Grover's quantum search algorithm
Physical Review A, 2003Co-Authors: Daniel Shapira, Shay Mozes, Ofer BihamAbstract:The effect of unitary noise on the performance of Grover's quantum search algorithm is studied. This type of noise may result from tiny fluctuations and drift in the parameters of the (quantum) components performing the computation. The resulting operations are still unitary, but not precisely those assumed in the design of the algorithm. Here we focus on the effect of such noise in the Hadamard Gate W, which is an essential component in each iteration of the quantum search process. To this end W is replaced by a noisy Hadamard Gate U. The parameters of U at each iteration are taken from an arbitrary probability distribution (e.g., a Gaussian distribution) and are characterized by their statistical moments around the parameters of W. For simplicity, we assume that the noise is unbiased and isotropic, namely, all noise variables in the parametrization we use have zero average and the same standard deviation {epsilon}. The noise terms at different calls to U are assumed to be uncorrelated. For a search space of size N=2{sup n} (where n is the number of qubits used to span this space) it is found that as long as {epsilon}
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effect of unitary noise on grover s quantum search algorithm
Physical Review A, 2003Co-Authors: Daniel Shapira, Shay Mozes, Ofer BihamAbstract:The effect of unitary noise on the performance of Grover's quantum search algorithm is studied. This type of noise may result from tiny fluctuations and drift in the parameters of the (quantum) components performing the computation. The resulting operations are still unitary, but not precisely those assumed in the design of the algorithm. Here we focus on the effect of such noise in the Hadamard Gate W, which is an essential component in each iteration of the quantum search process. To this end W is replaced by a noisy Hadamard Gate U. The parameters of U at each iteration are taken from an arbitrary probability distribution (e.g., a Gaussian distribution) and are characterized by their statistical moments around the parameters of W. For simplicity, we assume that the noise is unbiased and isotropic, namely, all noise variables in the parametrization we use have zero average and the same standard deviation {epsilon}. The noise terms at different calls to U are assumed to be uncorrelated. For a search space of size N=2{sup n} (where n is the number of qubits used to span this space) it is found that as long as {epsilon}
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Effect of unitary noise on Grover's quantum search algorithm
Physical Review A, 2003Co-Authors: Daniel Shapira, Shay Mozes, Ofer BihamAbstract:The effect of unitary noise on the performance of Grover's quantum search algorithm is studied. This type of noise may result from tiny fluctuations and drift in the parameters of the (quantum) components performing the computation. The resulting operations are still unitary, but not precisely those assumed in the design of the algorithm. Here we focus on the effect of such noise in the Hadamard Gate $W$, which is an essential component in each iteration of the quantum search process. To this end $W$ is replaced by a noisy Hadamard Gate $U$. The parameters of $U$ at each iteration are taken from an arbitrary probability distribution (e.g. Gaussian distribution) and are characterized by their statistical moments around the parameters of $W$. For simplicity we assume that the noise is unbiased and isotropic, namely all noise variables in the parametrization we use have zero average and the same standard deviation $\epsilon$. The noise terms at different calls to $U$ are assumed to be uncorrelated. For a search space of size $N=2^n$ (where $n$ is the number of qubits used to span this space) it is found that as long as $\epsilon < O(n^{-{1/2}} N^{-{1/4}})$, the algorithm maintains significant efficiency, while above this noise level its operation is hampered completely. It is also found that below this noise threshold, when the search fails, it is likely to provide a state that differs from the marked state by only a few bits. This feature can be used to search for the marked state by a classical post-processing, even if the quantum search has failed, thus improving the success rate of the search process
Lars Bojer Madsen - One of the best experts on this subject based on the ideXlab platform.
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Geometric phases in open tripod systems
Physical Review A, 2008Co-Authors: Ditte Moller, Lars Bojer Madsen, Klaus MølmerAbstract:We first consider stimulated Raman adiabatic passages in a closed four-level tripod system. In this case, the adiabatic eigenstates of the system acquire real geometric phases. When the system is open and subject to decoherence they acquire complex geometric phases that we determine by a Monte Carlo wave function approach. We calculate the geometric phases and the state evolution in the closed as well as in the open system cases and describe the deviation between these in terms of the phases acquired. When the system is closed, the adiabatic evolution implements a Hadamard Gate. The open system implements an imperfect Gate and hence has a fidelity below unity. We express this fidelity in terms of the acquired geometric phases.
-
Geometric phase Gates based on stimulated Raman adiabatic passage in tripod systems
Physical Review A, 2007Co-Authors: Ditte Moller, Lars Bojer Madsen, Klaus MølmerAbstract:We consider stimulated Raman adiabatic passage (STIRAP) processes in tripod systems and show how to generate purely geometric phase changes of the quantum states involved. The geometric phases are controlled by three laser fields where pulse shapes, relative field strength, and phases can be controlled. We present a robust set of universal Gates for quantum computing based on these geometric phases: a one-qubit phase Gate, a Hadamard Gate, and a two-qubit phase Gate.
-
Geometric phase Gates based on stimulated Raman adiabatic passage in tripod systems
Physical Review A, 2007Co-Authors: Ditte Moller, Lars Bojer Madsen, Klaus MølmerAbstract:We consider stimulated Raman adiabatic passage (STIRAP) processes in tripod systems and show how to generate purely geometric phase changes of the quantum states involved. The geometric phases are controlled by three laser fields where pulse shapes, relative field strength and phases can be controlled. We present a robust set of universal Gates for quantum computing based on these geometric phases: a one-qubit phase Gate, a Hadamard Gate and a two-qubit phase Gate.Comment: 6 pages, 3 figure