Abstract We report the experimental realization of the “active” quantum teleportation (QST) of a one‐particle entangled qubit. The qubit is physically implemented by a two‐dimensional subspace of states of a mode of the electromagnetic field, specifically, the space spanned by the vacuum and the one photon state. This demonstration completes the original QST protocol and renders it available for actual implementation in quantum computation networks. It is accomplished by implementing a 8 m optical delay line and a single‐photon triggered fast Electro‐Optic Pockels cell. A large value of teleportation “fidelity” was attained: Fa = 90 ∓ 2)%. Furthermore we present a scheme for delayed‐entanglement swapping by applying the same quantum optical method.Abstract We report the experimental realization of the “active” quantum teleportation (QST) of a one‐particle entangled qubit. The qubit is physically implemented by a two‐dimensional subspace of states of a mode of the electromagnetic field, specifically, the space spanned by the vacuum and the one photon state. This demonstration completes the original QST protocol and renders it available for actual implementation in quantum computation networks. It is accomplished by implementing a 8 m optical delay line and a single‐photon triggered fast Electro‐Optic Pockels cell. A large value of teleportation “fidelity” was attained: Fa = 90 ∓ 2)%. Furthermore we present a scheme for delayed‐entanglement swapping by applying the same quantum optical method.

Fortschritte der PhysikApr 24, 20031 citation

Recurrence formula for generalized optical state truncation by projection synthesis

Celso J. Villas-Bôas, Y. Guimarães, M. H. Y. Moussa +1 more

A recent work [Pegg et al., Phys. Rev. Lett. 81, 1604 (1998)] showed how to generate a running-wave superposition of zero- and one-photon field states, ${C}_{0}|0〉{+C}_{1}|1〉,$ by physical truncation of the photon number superposition making up a coherent state. Here we discuss the extension of this device to the case of N components: ${C}_{0}|0〉{+C}_{1}|1〉+\ensuremath{\cdot}\ensuremath{\cdot}\ensuremath{\cdot}{+C}_{N}|N〉.$A recent work [Pegg et al., Phys. Rev. Lett. 81, 1604 (1998)] showed how to generate a running-wave superposition of zero- and one-photon field states, ${C}_{0}|0〉{+C}_{1}|1〉,$ by physical truncation of the photon number superposition making up a coherent state. Here we discuss the extension of this device to the case of N components: ${C}_{0}|0〉{+C}_{1}|1〉+\ensuremath{\cdot}\ensuremath{\cdot}\ensuremath{\cdot}{+C}_{N}|N〉.$

Physical Review AApr 18, 200151 citations

NON-EQUIVALENCE OF THE TWO DEFINITIONS OF THE TWO-PHOTON COHERENT STATE

Peng Zhou, Jian Peng

Chinese Science BulletinJan 1, 19910 citations

The quantum mechanics of photon addition and subtraction

Myungshik Kim

In atomic-scale or quantum physics, an electromagnetic field is composed of photons, optical packets so small that a typical laser pointer with 1mW of power emits billions of them each second. Being able to take away or add a single photon in a light field at will would be useful for accurate engineering of quantum states. Such pure single photons are ideal for carrying and manipulating information in emerging quantum technologies, but generating them still is very challenging. In quantum physics, subtraction or addition of a photon is not a deterministic process. Instead, the probability is proportional to the number of photons originally in the electromagnetic field. This is described by the equation â|n〉 = √ n|n − 1〉 and â†|n〉 = √ n+ 1|n + 1〉, where â and â† are annihilation and creation operators, respectively, representing the action of subtracting and adding a photon in a field composed of n photons.1 Such single-photon operations were limited to pure theoretical discussions until 2004, when Grangier and coworkers found a simple way to subtract a photon2 from a field. Passing through a beam splitter of high transmittivity, some photons can be split from the initial field. A ‘click’ detected in the photodetector in the reflected channel means one photon has been subtracted from the field: see Figure 1(a). When the initial field is composed of a small number of photons, the effect is dramatic and may even completely change the characteristics of the field. For example, let us take an initial single-mode squeezed state generated by ‘degenerate’ parametric down-conversion, which is an optical nonlinear process that converts a pump photon into two twin photons with half the pump photon energy. (This state is well known for its quantum noise squeezed into one quadrature at the expense of expanded noise in the other quadrature.) In order to visualize the noise properties and characteristics of the squeezed state, a probability-like function, such Figure 1. Setups to subtract (a) and add (b) a single photon from/to a light field. ρin and ρout denote the density operators of the input and output fields; BS is a low-reflectivity beam splitter; PDC is a nonlinear crystal where parametric down-conversion takes place; â and â† denote on/off photodetectors.In atomic-scale or quantum physics, an electromagnetic field is composed of photons, optical packets so small that a typical laser pointer with 1mW of power emits billions of them each second. Being able to take away or add a single photon in a light field at will would be useful for accurate engineering of quantum states. Such pure single photons are ideal for carrying and manipulating information in emerging quantum technologies, but generating them still is very challenging. In quantum physics, subtraction or addition of a photon is not a deterministic process. Instead, the probability is proportional to the number of photons originally in the electromagnetic field. This is described by the equation â|n〉 = √ n|n − 1〉 and â†|n〉 = √ n+ 1|n + 1〉, where â and â† are annihilation and creation operators, respectively, representing the action of subtracting and adding a photon in a field composed of n photons.1 Such single-photon operations were limited to pure theoretical discussions until 2004, when Grangier and coworkers found a simple way to subtract a photon2 from a field. Passing through a beam splitter of high transmittivity, some photons can be split from the initial field. A ‘click’ detected in the photodetector in the reflected channel means one photon has been subtracted from the field: see Figure 1(a). When the initial field is composed of a small number of photons, the effect is dramatic and may even completely change the characteristics of the field. For example, let us take an initial single-mode squeezed state generated by ‘degenerate’ parametric down-conversion, which is an optical nonlinear process that converts a pump photon into two twin photons with half the pump photon energy. (This state is well known for its quantum noise squeezed into one quadrature at the expense of expanded noise in the other quadrature.) In order to visualize the noise properties and characteristics of the squeezed state, a probability-like function, such Figure 1. Setups to subtract (a) and add (b) a single photon from/to a light field. ρin and ρout denote the density operators of the input and output fields; BS is a low-reflectivity beam splitter; PDC is a nonlinear crystal where parametric down-conversion takes place; â and â† denote on/off photodetectors.

SPIE NewsroomJan 1, 20084 citations

Unpolarized light states in quantum optics

V. P. Karasev, Anatoly Viktorovich Masalov

Optics and SpectroscopyMay 1, 199320 citations

A recent work [Pegg et al., Phys. Rev. Lett. 81, 1604 (1998)] showed how to generate a running-wave superposition of zero- and one-photon field states,

{C}_{0}|0〉{+C}_{1}|1〉,

by physical truncation of the photon number superposition making up a coherent state. Here we discuss the extension of this device to the case of N components: ${C}_{0}|0〉{+C}_{1}|1〉+\ensuremath{\cdot}\ensuremath{\cdot}\ensuremath{\cdot}{+C}_{N}|N〉.$