Experimentally determined density matrices for H(n=3) formed in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">H</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>-He collisions from 20 to 100 keV

Ashburn, J; Cline, R. A.; Burgt, P J M van der; Westerveld, W. B.; Risley, John S.

doi:10.1103/physreva.41.2407

Cited by 64 publications

(29 citation statements)

References 18 publications

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“…It is however impossible to infer anything about an unknown state from a single measurement, a complete characterization requires an ensemble of identically prepared states and the measurement of a complete set of observables on the state [2]. A reconstruction of the quantum state wavefunction via such a series of measurements is known as Quantum State Tomography (QST) [3].Initially, QST was performed experimentally on the discrete angular momentum state of an electron in an hydrogen atom [4]. During the last decade QST has been performed on e.g.…”

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confidence: 99%

Quantum state tomography with quantum shot noise

Samuelsson

Büttiker

2006

Phys. Rev. B

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We propose a scheme for a complete reconstruction of one-and two-particle orbital quantum states in mesoscopic conductors. The conductor in the transport state continuously emits orbital quantum states. The orbital states are manipulated by electronic beamsplitters and detected by measurements of average currents and zero frequency current shotnoise correlators. We show how, by a suitable complete set of measurements, the elements of the density matrices of the one-and two-particle states can be directly expressed in terms of the currents and current correlators.PACS numbers: 03.67. Mn,42.50.Lc, According to the standard interpretation of quantum mechanics the wavefunction, or more generally the density matrix, determines the probabilities for the possible outcomes of any measurement on the quantum state. To completely characterize the wavefunction of the state is therefore of fundamental interest [1]. It is however impossible to infer anything about an unknown state from a single measurement, a complete characterization requires an ensemble of identically prepared states and the measurement of a complete set of observables on the state [2]. A reconstruction of the quantum state wavefunction via such a series of measurements is known as Quantum State Tomography (QST) [3].Initially, QST was performed experimentally on the discrete angular momentum state of an electron in an hydrogen atom [4]. During the last decade QST has been performed on e.g. the quantum state of squeezed light [5], the vibrational state of a molecule [6], the motional state of trapped ions [7] and of atomic wavepackets [8]. Recently there has been an interest in QST of two-particle states in the context of quantum information processing. The entanglement of a quantum state, a potential resource for quantum information processing, is characterized by the density matrix of the state. The quantum state of polarization entangled pairs of photons has been reconstructed using QST [9].To date, no QST has been performed on quantum states in solid state systems. Very recently a theoretical scheme [10] was developed for solid state two-levels systems, qubits, appropriate for e.g. the macroscopic superposition state in superconducting qubits and the spinstate of electrons in quantum dots. The set of measurements necessary to reconstruct the state involves controlled rotations and detection of the individual qubits. For coupled qubits, where entanglement between the qubits is of interest, such measurements are highly involved and have not been demonstrated.In this paper we take a different approach and present a scheme for QST of discrete single and two-particle orbital quantum states in mesoscopic conductors. The orbital quantum states [11,12,13] are continuously emitted from the conductor during transport, making a long time measurement equivalent to an average over an ensemble of states. The orbital states can be manipulated by electronic beamsplitters, experimentally available [14,15], and detected by measurements of average currents and zero frequen...

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confidence: 99%

Quantum state tomography with quantum shot noise

Samuelsson

Büttiker

2006

Phys. Rev. B

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“…By measuring the population numbers of these field-dependent eigenstates, one actually investigates the projections of the impact-excited state on various basis vectors. From these measurements the impact-excited state can finally be reconstructed [7]. Due to the instantaneouslike excitation, the assumption is reasonable that the actual collision process is not affected by the external fields.…”

Section: Atlas~rementioning

confidence: 99%

Angular momentum coherences of helium atoms excited by proton impact

Oppen

Büttrich

1994

Z Phys D - Atoms, Molecules and Clusters

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Abstract. Using electric-field anticrossing techniques, we investigated the coherent excitation of n = 5-8 He I states with different orbital angular momenta by proton impact. These measurements give strong evidence that saddle dynamics of Hf-tike systems are well suited for describing the final phase of 12.5 keV H+-He collisions. We conclude that, besides electron promotion via the 2po-orbital, the collision system undergoes diabatic l sa-3da transitions during the close encounter and present an explanation of the electric dipole moments measured for excitation of H(n=2) states by H+-He and H-He collisions.

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“…These coherence parameters, for example the orientation and alignment parameters, the dipole moment of the degenerate excited states of atomic hydrogen, can be determined experimentally by measuring the angular distribution and/or polarization of the emitted radiations [1,3] with or without an external electric field. These parameters have been calculated theoretically by the distorted wave Born approximation for collisions of electrons and positrons with atoms [-4-6], and by the close-coupling method for collisions of heavy ions with atoms [7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Coherence parameters of atomic excited states: comparison of results from the CTMC and the quantal calculations

Toshima

Lin

1991

Z Phys D - Atoms, Molecules and Clusters

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Abstract. The coherence parameters of excited states formed in collisions of atoms with electrons, positrons, protons and antiprotons are calculated using the Classical Trajectory Monte Carlo (CTMC) method and the results are compared to those obtained from the quantal distorted wave and close-coupling calculations. The orientation parameter and the components of the electric dipole moment of the electronic charge cloud after the collision are examined for excitation and for electron capture to H(n=2) states. It is found that the CTMC results are in qualitative agreement with the quantal distorted wave and close-coupling results for some of the coherent parameters only.

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Experimentally determined density matrices for H(n=3) formed inH+-He collisions from 20 to 100 keV

Cited by 64 publications

References 18 publications

Quantum state tomography with quantum shot noise

Quantum state tomography with quantum shot noise

Angular momentum coherences of helium atoms excited by proton impact

Coherence parameters of atomic excited states: comparison of results from the CTMC and the quantal calculations

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