Beyond the Four-Level Model: Dark and Hot States in Quantum Dots Degrade Photonic Entanglement.

Entangled photon pairs are essential for a multitude of quantum photonic applications. To date, the best performing solid-state quantum emitters of entangled photons are semiconductor quantum dots operated around liquid-helium temperatures. To favor the widespread deployment of these sources, it is important to explore and understand their behavior at temperatures accessible with compact Stirling coolers. Here we study the polarization entanglement among photon pairs from the biexciton-exciton cascade in GaAs quantum dots at temperatures up to ∼65 K. We observe entanglement degradation accompanied by changes in decay dynamics, which we ascribe to thermal population and depopulation of hot and dark states in addition to the four levels relevant for photon pair generation. Detailed calculations considering the presence and characteristics of the additional states and phonon-assisted transitions support the interpretation. We expect these results to guide the optimization of quantum dots as sources of highly entangled photons at elevated temperatures.

Treatment with brentuximab vedotin plus bendamustine in unselected patients with CD30-positive aggressive lymphomas.

OBJECTIVES: A treatment regimen consisting of bendamustine and brentuximab vedotin (BV) has been described as a highly potent salvage therapy and as an effective induction therapy leading to high response rates before autologous stem cell transplantation (ASCT) in patients with classical Hodgkin lymphoma (cHL). In this retrospective analysis, we aimed to assess this therapy's efficacy in unselected patients with cHL and CD30+ peripheral T-cell lymphoma (PTCL). PATIENTS AND METHODS: Data of 28 patients with cHL and five patients with PTCL treated with a combination of bendamustine and BV at three Austrian tertiary cancer centers were analyzed. RESULTS: In patients with cHL, the ORR was 100% (78.6% CR, 21.4% PR). After 17 months median follow-up, median survival times were not reached; 1-year PFS was 81.9%, and 1-year OS was 95.7%. Thirteen eligible patients (46.4%) successfully underwent planned ASCT after salvage therapy with bendamustine and BV and subsequent high-dose chemotherapy. Three of the five PTCL patients achieved CR, while two did not respond and died during or shortly after therapy. CONCLUSION: A combination of bendamustine and BV is an effective salvage and induction therapy before ASCT in patients with relapsed/refractory cHL. Further research is warranted to evaluate the use in patients with PTCL.

The Blood Group A Genotype Determines the Level of Expression of the Blood Group A on Platelets But Not the Anti-B Isotiter.

BACKGROUND: The extent of expression of the blood group A on platelets is controversial. Further, the relation between platelets' blood group A expression and the titers of isoagglutinins has not been thoroughly investigated, so far. METHODS: We evaluated the relation between the genotype with platelets' blood group A and H expression estimated by flow cytometry and the titers of isoagglutinins. RESULTS: The A expression varied between genotypes and within genotypes. However, the expression in A1 was stronger than in all other genotypes (p < 0.0001). An overlap of expression levels was apparent between homozygous A1A1 and heterozygous A1 individuals. Still, The A1A1 genotype is associated with a particularly high antigen expression (p = 0.009). Platelets' A expression in A2 versus blood group O donors was also significant (p = 0.007), but there was again an overlap of expression. The secretor status had only little influence on the expression (p = 0.18). Also, isoagglutinin titers were not associated with genotypes. CONCLUSION: To distinguish between A1 and A2 donors may reduce incompatible platelet transfusions and therefore be favorable on platelet transfusion increment. Clinical data are needed to support this notion.

Quantum cryptography with highly entangled photons from semiconductor quantum dots.

Semiconductor quantum dots are capable of emitting polarization entangled photon pairs with ultralow multipair emission probability even at maximum brightness. Using a quantum dot source with a fidelity as high as 0.987(8), we implement here quantum key distribution with an average quantum bit error rate as low as 1.9% over a time span of 13 hours. For a proof of principle, the key generation is performed with the BBM92 protocol between two buildings, connected by a 350-m-long fiber, resulting in an average raw (secure) key rate of 135 bits/s (86 bits/s) for a pumping rate of 80 MHz, without resorting to time- or frequency-filtering techniques. Our work demonstrates the viability of quantum dots as light sources for entanglement-based quantum key distribution and quantum networks. By increasing the excitation rate and embedding the dots in state-of-the-art photonic structures, key generation rates in the gigabits per second range are in principle at reach.