More Like this

1. Young's double-slit interference demonstration with single photons

   https://doi.org/10.1119/5.0179131  

   Luo, Bill J; Francis, Leia; Rodríguez-Fajardo, Valeria; Galvez, Enrique J; Khoshnoud, Farbod (April 2024, American Journal of Physics)

   This article presents a table-top experiment that acquires the interference pattern from single photons passing through a double-slit. The experiment is carried out using the heralded, single-photon experimental setup now affordable and fairly common in advanced instructional laboratories. By scanning a single-photon detector on a translation stage, this experiment is implemented without the need of an expensive gate-intensified CCD camera. The authors compare the acquired single-slit and double-slit interference patterns to predicted ones and include a quantum eraser measurement. The experiments are dramatic demonstrations of wave-particle quantum effects and are excellent additions to the collection of single-photon experiments that have been developed over the past several years for the advanced instructional laboratory curriculum. 

   more » « less
2. Quantum mechanical double slit for molecular scattering

   https://doi.org/10.1126/science.abl4143  

   Zhou, Haowen; Perreault, William E.; Mukherjee, Nandini; Zare, Richard N. (November 2021, Science)

   Interference observed in a double-slit experiment most conclusively demonstrates the wave properties of particles. We construct a quantum mechanical double-slit interferometer by rovibrationally exciting molecular deuterium (D 2 ) in a biaxial ( v = 2, j = 2) state using Stark-induced adiabatic Raman passage, where v and j represent the vibrational and rotational quantum numbers, respectively. In D 2 ( v = 2, j = 2) → D 2 ( v = 2, j ′ = 0) rotational relaxation via a cold collision with ground state helium, the two coherently coupled bond axis orientations in the biaxial state act as two slits that generate two indistinguishable quantum mechanical pathways connecting initial and final states of the colliding system. The interference disappears when we decouple the two orientations of the bond axis by separately constructing the uniaxial states of D 2 , unequivocally establishing the double-slit action of the biaxial state. This double slit opens new possibilities in the coherent control of molecular collisions. 

   more » « less
3. A revised double-slit experiment to explore the mechanism of photon wavefunction collapse by numerical design

   https://doi.org/10.1063/5.0207981  

   Wang, Ankai; Zhang, Jixuan; Zou, Shengli (May 2024, AIP Advances)

   The double-slit experiment has long been pivotal in understanding matter’s wave–particle duality. A central question revolves around Born’s interpretation of wavefunction whether a single photon demonstrates a 50% probability of passing through each slit individually as particles or simultaneously traverses both as waves. Experimentally, once the photon’s path is detected, the observer effect causes its wavefunction to collapse, rendering the results inconclusive. Designing an experiment to minimize instrumental involvement during the wavefunction collapse of photons, while aiming to gain insight into its collapse mechanism, becomes necessary. We propose a revised experiment that replaces the traditional setup with two Au nanoparticles acting as observers, triggering photon collapse before spectrum collection. In single-photon scenarios, we consider two assumptions: first, the photon wavefunctions collapse into a particle and transfer energy to one of the nanoparticles exclusively, and second, the photon acts as a wave, splitting and transferring its energy to two nanoparticles simultaneously, which does not align well with Born’s interpretation of wavefunction as spatial probabilities. These two assumptions would generate distinctly different spectra. Conversely, in high-intensity experiments, both nanoparticles collectively undergo excitation, regardless of the collapse mechanism. A comparative analysis of scattering spectra under the two conditions reveals crucial insights into the genuine nature of photon collapse. We also proposed using two molecules attached to a metal nanoparticle as an alternative design. Whether affirming or refuting the observer effect, this research holds promise for resolving the theoretical debate surrounding the collapse of wavefunctions and advancing quantum computing and communication fields. 

   more » « less
4. Investigation of student and faculty problem solving: An example from quantum mechanics

   https://doi.org/10.1119/5.0207947  

   Maries, Alexandru; Sayer, Ryan; Singh, Chandralekha (June 2025, American journal of physics)

   Parks, Beth (Ed.)

   We describe a study focusing on students' and faculty members' reasoning about problems of differing cognitive complexity related to the double-slit experiment (DSE) with single particles. In the first phase of the study, students in advanced quantum mechanics courses were asked these questions in written form. Additionally, individual interviews were conducted with ten students in which they were asked follow-up questions to make their thought processes explicit on the challenging problems. Students did well on the straightforward problem, showing they had some knowledge of the DSE after traditional instruction, but they struggled on the more complex ones. Even if explicitly asked to do so in interviews, students were often uncomfortable performing calculations or making approximations and simplifications, instead preferring to stick with their gut feeling. In the second phase of the study, the problems were broken down into more pointed questions to investigate whether students had knowledge of relevant concepts, whether they would do calculations as part of their solution approach if explicitly asked, and whether they explicitly noted using their gut feeling. While the faculty members' responses suggest that they could seamlessly move between conceptual and quantitative reasoning, most students were unable to combine concepts represented by different equations to solve the problems quantitatively. We conclude with instructional implications. 

   more » « less
5. Do students think that objects have a true definite position?

   https://doi.org/10.1103/PhysRevPhysEducRes.20.010154  

   Stump, Emily M; Hughes, Mark; Holmes, N G; Passante, Gina (June 2024, Physical Review Physics Education Research)

   Previous research on student thinking about experimental measurement and uncertainty has primarily focused on students’ procedural reasoning: Given some data, what should students calculate or do next? This approach, however, cannot tell us what beliefs or conceptual understanding leads to students’ procedural decisions. To explore this relationship, we first need to understand the range of students’ beliefs and conceptual understanding of measurement. In this work, we explored students’ philosophical beliefs about the existence of a true value in experimental measurement. We distributed a survey to students from 12 universities in which we presented two viewpoints on the existence of a true definite position resulting from an experiment, asking participants to indicate which view they agreed with more and asking them to explain their choice. We found that participants, both students and experts, varied in their beliefs about the existence of a true definite position and discussed a range of concepts related to quantum mechanics and the experimental process to explain their answers, regardless of whether or not they agreed with the existence of a true value. From these results, we postulate that students who exhibit similar procedural reasoning may hold widely varying philosophical views about measurement. We recommend that future work investigates this potential relationship and whether and how instruction should attend to these philosophical views in addition to students’ procedural decisions. 

   more » « less