Ultrabright source of polarization-entangled photons

May combine two claims.

Following [10], the measurements may be combined to yield S = 2.7007 ± 0.0029, where according to any local realistic theory |S| ≤ 2 and the maximum according to quantum mechanics is 2√2.

“Following [10], these may be combined to yield a value for the parameter S = 2 . 7007 ± 0 . 0029, where according to any local realistic theory | S | ≤ 2 (and the maximum according to quantum mechanics is 2 √ 2).”

• cites [10] sourceNot checked yet

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May combine two claims.

In the second set of measurements with a vertical slit of width 3.5 mm added after each iris and varying vertical dimension, the visibility stayed essentially constant at about 95%, but the coincidence rate still increased.

“In the second set of measurements (Fig. 3b), a vertical slit of width 3.5mm was added after each iris, and the vertical dimension of the aperture was varied using the iris size; this effectively collects a larger portion of the same cone. The visibility then stayed essentially constant at ∼ 95%, but the coincidence rate still increased.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The collection irises for this data were both only 1.76 mm in diameter, and the resulting collection efficiency is then about 10%.

“The collection irises for this data were both only 1.76 mm in diameter - the resulting collection efficiency (the probability of collecting one photon conditioned on collecting the other) is then ∼ 10%.”

May combine two claims.

With the state set to HH - VV and the polarization analyzer in path 1 at -45°, the coincidence rate displayed sinusoidal fringes with nearly perfect visibility V = 99.6 ± 0.3% with accidental coincidences subtracted and 98.8 ± 0.2% with them included.

“As expected, the coincidence rate displayed sinusoidal fringes with nearly perfect visibility ( V = 99 . 6 ± 0 . 3% with 'accidental' coincidences subtracted; 98 . 8 ± 0 . 2% with them included)”

May combine two claims.

In the first set of data with circular irises, the visibility decreased somewhat as the iris size increased, while the coincidence rate normalized by the input pump power increased.

“In the first set of data (Fig. 3a), circular irises were used; the visibility decreased somewhat as the iris size increased, while the coincidence rate (normalized by the input pump power) increased.”

Classified as probably not a substantial claim.

The photons produced via the down-conversion process share nonclassical correlations.

“It is now well known that the photons produced via the down-conversion process share nonclassical correlations [7].”

• cites [7] sourceNot checked yet

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Probably not a substantial claim: may not pass S3 (load-bearing).

When a pump photon splits into two daughter photons, conservation of energy and momentum lead to entanglements in two continuous degrees of freedom.

“conservation of energy and momentum lead to entanglements in these two continuous degrees of freedom [8]”

• cites [8] sourceNot checked yet

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Probably not a substantial claim: may not pass S4 (based).

The new technique has the added advantage that the degree of entanglement and the purity of the state may be readily tunable, which was heretofore impossible.

“The new technique has the added advantage that the degree of entanglement and the purity of the state may be readily tunable, heretofore impossible.”

May combine two claims.

In the two-crystal geometry with type-I phase-matching, with a vertically polarized pump beam, down-conversion will only occur in crystal 1, where the pump is extraordinary polarized, and the resulting down-conversion light cones will be horizontally polarized.

“With a vertically polarized pump beam, due to the type-I coupling, down-conversion will only occur in crystal 1, where the pump is extraordinary polarized - the resulting down-conversion light cones will be horizontally polarized.”

May combine two claims.

φ is determined by the details of the phase-matching and the crystal thickness, but can be adjusted by tilting the BBO crystals themselves, by imposing a birefringent phase shift on one of the output beams, or by controlling the relative phase between the horizontal and vertical components of the pump light.

“φ is determined by the details of the phase-matching and the crystal thickness, but can be adjusted by tilting the BBO crystals themselves (but this changes the cones' opening angles), by imposing a birefringent phase shift on one of the output beams, or by controlling the relative phase between the horizontal and vertical components of the pump light.”

May combine two claims.

Because nearly every pair of photons produced is polarization-entangled, the total flux of emitted polarization-entangled pairs should be hundreds of times greater than is achievable with the best previous source, for comparable pump powers.

“Because nearly every pair of photons produced is polarization-entangled, the total flux of emitted polarization-entangled pairs should be hundreds of times greater than is achievable with the best previous source, for comparable pump powers.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

Both the degree of entanglement and the state purity should be readily tunable.

“both the degree of entanglement and the state purity should be readily tunable”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Another factor of 30 to 75 in brightness is expected to be readily achievable.

“with another factor of 30 to 75 expected to be readily achievable”

May combine two claims.

To date there have been only two methods for producing polarization-entangled photon pairs, and each has fairly substantial limitations.

“To date there have been only two methods for producing such polarization-entangled photon pairs, and each has fairly substantial limitations.”

• cites [9] sourceNot checked yet

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• cites [10] sourceNot checked yet

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• cites [11] sourceNot checked yet

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• cites [12] sourceNot checked yet

  Not checked in the free run.

May combine two claims.

For two particular emission directions in the type-II source, the correlated photons are produced in the state HV + VH; additional birefringent elements in one or both beams allow the formation of all four Bell states.

“For two particular emission directions, however, the correlated photons are produced in the state HV + V H ; additional birefringent elements in one or both beams allow the formation of all four Bell states.”

• cites [12] sourceNot checked yet

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May combine two claims.

This is about 300 times brighter than the polarization-entangled photon-pair production rates obtainable with the previous down-conversion scheme, and 750 times brighter if scaled by the crystal thickness.

“This is ∼ 300 times brighter than the polarization-entangled photon-pair production rates obtainable with the previous down-conversion scheme [12], (and 750 times brighter if scaled by the crystal thickness).”

• cites [12] sourceNot checked yet

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May combine two claims.

For all detected down-conversion photons to be described by essentially the same polarization-entangled state, the bandwidth of acceptance needs to be restricted, the crystal thicknesses reduced, or a special birefringent compensation element included.

“For all detected down-conversion photons to be described by essentially the same polarizationentangled state, the bandwidth of acceptance needs to be restricted, the crystal thicknesses reduced, or a special birefringent compensation element included.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

The authors believe this to be the highest purity entangled state ever reported.

“We believe this to be the highest purity entangled state ever reported.”

May combine two claims.

The source may be used to produce non-maximally entangled states of the form HH + ε VV, |ε| = 1, simply by rotating the pump polarization; for a pump polarized at angle θ to the vertical, ε = tan θ.

“Another remarkable feature of this source is that it may be used to produce 'non-maximally entangled' states, i.e., states of the form HH + ǫV V , | ǫ | = 1, simply by rotating the pump polarization - for a pump polarized at angle θ to the vertical, ǫ = tan θ .”

Probably not a substantial claim: may not pass S3 (load-bearing).

Just as with the previous type-II source, the other two Bell states HV ± VH may be prepared simply by inserting a half waveplate in one of the arms to exchange H and V polarization.

“Just as with the previous typeII source [12], the other two Bell states HV ± V H may be prepared simply by inserting a half waveplate in one of the arms to exchange H and V polarization.”

• cites [12] sourceNot checked yet

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May combine two claims.

For 150-mW pump power, this implies a coincidence rate of 21,000 s−1, a ×10 increase over the previous type-II source, which used a BBO crystal 2.5 times longer.

“For 150-mW pump power, this implies a coincidence rate of 21,000s -1 [22], a × 10 increase over the previous typeII source (which used a BBO crystal 2.5 times longer [12]).”

• cites [12] sourceNot checked yet

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• cites [22] Signficantly, this is roughly the minimum rate for quantum cryptography in an earth-to-satellite configuration [W. T. Buttler et al ., Phys. Rev. Lett. 81 , 3283 (1998)]. φ also depends on the azimuthal angle of production photons from crystal 1 are extraordinarily-polarized in crystal 2, so the refractive index depends on direction. Our total azimuthal variation in φ was < 0 . 02 ◦ ; this could be eliminated entirely by adding a compensation crystal identical in size and orientation to crystal 2. sourceNot checked yet

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May combine two claims.

Given the symmetry of the arrangement, the authors expect strong entanglement over the entire cone, implying a total polarization-entangled pair production rate over the 5-nm bandwidth of about 10,000 s−1 mW−1, after dividing out filter transmissions and detector efficiencies.

“Given the symmetry of the arrangement, we expect strong entanglement over the entire cone, implying a total polarization-entangled pair production rate (over the 5-nm bandwidth) of about 10,000 s -1 mW -1 , where we have divided out the filter transmissions and detector efficiencies.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Hyper-entangled states may benefit certain experiments in quantum information.

“and it has been shown that such states may benefit certain experiments in quantum information [15,29].”

• cites [15] sourceNot checked yet

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• cites [29] P. G. Kwiat and H. Weinfurter, Phys. Rev. A 58 , R2623 (1998). sourceNot checked yet

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May combine two claims.

Because the entanglement exists over the entire cones of emitted light, this source is much brighter than previous ones, allowing a tremendous Bell inequality violation in only minutes.

“Because the entanglement exists over the entire cones of emitted light, this source is much brighter than previous ones, allowing a tremendous Bell inequality violation in only minutes.”

Classified as probably not a substantial claim. May combine two claims.

Such brightness is completely necessary for some applications, like quantum cryptography to a satellite, and very advantageous for others, like teleportation, which requires two pairs of entangled photons and hence scales as the square of the source intensity.

“Such brightness is completely necessary for some applications (like quantum cryptography to a satellite), and very advantageous for others (like teleportation, which requires two pairs of entangled photons, and hence scales as the square of the source intensity).”

• cites [22] Signficantly, this is roughly the minimum rate for quantum cryptography in an earth-to-satellite configuration [W. T. Buttler et al ., Phys. Rev. Lett. 81 , 3283 (1998)]. φ also depends on the azimuthal angle of production photons from crystal 1 are extraordinarily-polarized in crystal 2, so the refractive index depends on direction. Our total azimuthal variation in φ was < 0 . 02 ◦ ; this could be eliminated entirely by adding a compensation crystal identical in size and orientation to crystal 2. sourceNot checked yet

  Not checked in the free run.

• cites [5] sourceNot checked yet

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