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Quantum algorithms for quantum field theories, Science 336
, 2012
"... Quantum field theory reconciles quantum mechanics and special relativity, and plays a central role in many areas of physics. We developed a quantum algorithm to compute relativistic scattering probabilities in a massive quantum field theory with quartic selfinteractions (f4 theory) in spacetime of ..."
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Quantum field theory reconciles quantum mechanics and special relativity, and plays a central role in many areas of physics. We developed a quantum algorithm to compute relativistic scattering probabilities in a massive quantum field theory with quartic selfinteractions (f4 theory) in spacetime of four and fewer dimensions. Its run time is polynomial in the number of particles, their energy, and the desired precision, and applies at both weak and strong coupling. In the strongcoupling and highprecision regimes, our quantum algorithm achieves exponential speedup over the fastest known classical algorithm. Thequestion whether quantum field theoriescan be efficiently simulated by quantumcomputers was first posed by Feynman three decades ago when he introduced the notion of quantum computers (1). Since then, efficient quantum algorithms for simulating the dynamics of quantum manybody systems have been developed theoretically (2–4) and demonstrated experimentally (5–7). Quantum field theory, which applies quantum mechanics to functions of space
Actively secure twoparty evaluation of any quantum operation. Cryptology ePrint Archive, record 2012/XXX, http://eprint.iacr. org
, 2012
"... Abstract. We provide the first twoparty protocol allowing Alice and Bob to evaluate privately even against active adversaries any completely positive, tracepreserving map F ∈ L(Ain ⊗ Bin) → L(Aout ⊗ Bout), given as a quantum circuit, upon their joint quantum input state ρin ∈ D(Ain ⊗ Bin). Our pro ..."
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Cited by 7 (0 self)
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Abstract. We provide the first twoparty protocol allowing Alice and Bob to evaluate privately even against active adversaries any completely positive, tracepreserving map F ∈ L(Ain ⊗ Bin) → L(Aout ⊗ Bout), given as a quantum circuit, upon their joint quantum input state ρin ∈ D(Ain ⊗ Bin). Our protocol leaks no more to any active adversary than an ideal functionality for F provided Alice and Bob have the cryptographic resources for active secure twoparty classical computation. Our protocol is constructed from the protocol for the same task secure against specious adversaries presented in [4]. We show how to transform it so that it preserves privacy against active adversaries as well. 1
OPTIMAL BACONSHOR CODES
, 2013
"... We study the performance of BaconShor codes, quantum subsystem codes which are well suited for applications to faulttolerant quantum memory because the error syndrome can be extracted by performing twoqubit measurements. Assuming independent noise, we find the optimal block size in terms of the b ..."
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Cited by 2 (0 self)
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We study the performance of BaconShor codes, quantum subsystem codes which are well suited for applications to faulttolerant quantum memory because the error syndrome can be extracted by performing twoqubit measurements. Assuming independent noise, we find the optimal block size in terms of the bitflip error probability pX and the phase error probability pZ, and determine how the probability of a logical error depends on pX and pZ. We show that a single BaconShor code block, used by itself without concatenation, can provide very effective protection against logical errors if the noise is highly biased (pZ/pX ≫ 1) and the physical error rate pZ is a few percent or below. We also derive an upper bound on the logical error rate for the case where the syndrome data is noisy.
Exploring adiabatic quantum trajectories via optimal control
"... Abstract. Adiabatic quantum computation employs a slow change of a timedependent control function (or functions) to interpolate between an initial and final Hamiltonian, which helps to keep the system in the instantaneous ground state. When the evolution time is finite, the degree of adiabaticity ( ..."
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Abstract. Adiabatic quantum computation employs a slow change of a timedependent control function (or functions) to interpolate between an initial and final Hamiltonian, which helps to keep the system in the instantaneous ground state. When the evolution time is finite, the degree of adiabaticity (quantified in this work as the average groundstate population during evolution) depends on the particulars of a dynamic trajectory associated with a given set of control functions. We use quantum optimal control theory with a composite objective functional to numerically search for controls that achieve the target final state with a high fidelity while simultaneously maximizing the degree of adiabaticity. Exploring properties of optimal adiabatic trajectories in model systems elucidates the dynamic mechanisms that suppress unwanted excitations from the ground state. Specifically, we discover that the use of multiple control functions makes it possible to access a rich set of dynamic trajectories, some of which attain a significantly improved performance (in terms of both fidelity and adiabaticity) through the increase of the energy gap during most of the evolution time. Submitted to: New J. Phys. † Author to whom any correspondence should be addressed. ar
SUFFICIENT CONDITION ON NOISE CORRELATIONS FOR SCALABLE QUANTUM COMPUTING
, 2013
"... I study the effectiveness of faulttolerant quantum computation against correlated Hamiltonian noise, and derive a sufficient condition for scalability. Arbitrarily long quantum computations can be executed reliably provided that noise terms acting collectively on k system qubits are sufficiently we ..."
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I study the effectiveness of faulttolerant quantum computation against correlated Hamiltonian noise, and derive a sufficient condition for scalability. Arbitrarily long quantum computations can be executed reliably provided that noise terms acting collectively on k system qubits are sufficiently weak, and decay sufficiently rapidly with increasing k and with increasing spatial separation of the qubits.
Home Search Collections Journals About Contact us My IOPscience Dynamically protected catqubits: a new paradigm for universal quantum computation
, 2013
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content has been downloaded from IOPscience. Please scroll down to see the full text.
Brief Announcement: The Impact of Classical Electronics Constraints on a SolidState Logical Qubit Memory
"... ABSTRACT We present and analyze an architecture for a logical qubit memory that is tolerant of faults in the processing of silicon double quantum dot (DQD) qubits. A highlight of our analysis is an indepth consideration of the constraints faced when integrating DQDs with classical control electron ..."
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ABSTRACT We present and analyze an architecture for a logical qubit memory that is tolerant of faults in the processing of silicon double quantum dot (DQD) qubits. A highlight of our analysis is an indepth consideration of the constraints faced when integrating DQDs with classical control electronics.