Delayed Choice Quantum Eraser Research Articles

Coherently excited superresolution using intensity product of phase-controlled quantum erasers via polarization-basis projection measurements

Recently, the delayed-choice quantum eraser has been applied for coherently excited superresolution using phase-controlled projection measurements of laser light to overcome the diffraction limit in classical physics as well as to solve the limited order N of the N00N state in quantum physics. Here, a general scheme of the phase-controlled quantum eraser-based superresolution is proposed for quantum sensing satisfying the Heisenberg limit, and its general solution is derived for an arbitrary Nth-order intensity correlation. Furthermore, phase quantization of the proposed superresolution is discussed to better understand the wave nature of quantum mechanics. Unlike other methods of superresolution in quantum sensing, the proposed method is for the intensity products between phase-controlled quantum erasers and thus is compatible with most conventional sensing metrologies.

Phase-controlled coherent photons for the quantum correlations in a delayed-choice quantum eraser scheme

The delayed-choice quantum eraser has been intensively studied for the wave-particle duality of a single photon in an interferometric system over the last decades. Super-resolution has been studied over decades for quantum sensing to overcome the standard quantum limit. For the super-resolution, either quantum features of higher-order entangled photon pairs or classical features of phase-controlled coherent photons have been successfully demonstrated. Here, a method of classically excited super-resolution is presented for the phase-controlled coherent photons in a quarter-wave plate-modified quantum eraser scheme. To support the underlying physics of the super-resolution, nonlocal correlation is also presented with an additional frequency-polarization basis control via selective product-basis measurements.

Complementarity relations of a delayed-choice quantum eraser in a quantum circuit

Complementarity relations of a delayed-choice quantum eraser in a quantum circuit

Coherently driven quantum features using a linear optics-based polarization-basis control

Quantum entanglement generation is generally known to be impossible by any classical means. According to Poisson statistics, coherent photons are not considered quantum particles due to the bunching phenomenon. Recently, a coherence approach has been applied for quantum correlations such as the Hong–Ou–Mandel (HOM) effect, Franson-type nonlocal correlation, and delayed-choice quantum eraser to understand the mysterious quantum features. In the coherence approach, the quantum correlation has been now understood as a direct result of selective measurements between product bases of phase-coherent photons. Especially in the HOM interpretation, it has been understood that a fixed sum-phase relation between paired photons is the bedrock of quantum entanglement. Here, a coherently excited HOM model is proposed, analyzed, and discussed for the fundamental physics of two-photon correlation using linear optics-based polarization-basis control. For this, polarization-frequency correlation in a Mach–Zehnder interferometer is coherently excited using synchronized acousto-optic modulators, where polarization-basis control is conducted via a selective measurement process of the heterodyne signals. Like quantum operator-based destructive interference in the HOM theory, a perfectly coherent analysis shows the same HOM effects of the paired coherent photons on a beam splitter, whereas individual output intensities are uniform.

Observations of the delayed-choice quantum eraser using coherent photons

Quantum superposition is the cornerstone of quantum mechanics, where interference fringes originate in the self-interference of a single photon via indistinguishable photon characteristics. Wheeler’s delayed-choice experiments have been extensively studied for the wave-particle duality over the last several decades to understand the complementarity theory of quantum mechanics. The heart of the delayed-choice quantum eraser is in the mutually exclusive quantum feature violating the cause-effect relation. Here, we experimentally demonstrate the quantum eraser using coherent photon pairs by the delayed choice of a polarizer placed out of the interferometer. Coherence solutions of the observed quantum eraser are derived from a typical Mach–Zehnder interferometer, where the violation of the cause-effect relation is due to selective measurements of basis choice.

Delayed-Choice Quantum Erasers and the Einstein-Podolsky-Rosen Paradox

Considering the delayed-choice quantum eraser using a Mach-Zehnder interferometer with a nonsymmetric beam splitter, we explicitly demonstrate that it shares exactly the same formal structure with the Einstein-Podolsky-Rosen-Bohm (EPR-Bohm) experiment. Therefore, the effect of quantum erasure can be understood in terms of the standard EPR correlation. Nevertheless, the quantum eraser still raises a conceptual issue beyond the standard EPR paradox, if counterfactual reasoning is taken into account. Furthermore, the quantum eraser experiments can be classified into two major categories: the entanglement quantum eraser and the Scully-Dr\"uhl-type quantum eraser. These two types are formally equivalent to each other, but conceptually the latter presents a "mystery" more prominent than the former. In the Scully-Dr\"uhl-type quantum eraser, the statement that the which-way information can be influenced by the delayed-choice measurement is not purely a consequence of counterfactual reasoning but bears some factual significance. Accordingly, it makes good sense to say that the "record" of the which-way information is "erased" if the potentiality to yield a conclusive outcome that discriminates the record is eliminated by the delayed-choice measurement. We also reconsider the quantum eraser in the many-worlds interpretation (MWI), making clear the conceptual merits and demerits of the MWI.

A Delayed-Choice Quantum Eraser with Photon-Counting MKIDs (Experimental Design)

An extension to the delayed-choice quantum eraser (DCQE) photonic experiment is described in this paper. It is proposed to employ an array of superconducting detectors on the measurement plane, and use their high sensitivity, low-noise, and fast response time to provide significantly better control of the system in a real-time, photon-counting format. We present an experimental design that would allow a pulse-triggered feedback loop to be added to be system, in an attempt to test an apparent information paradox. We show how new light might be shed on the interpretations and conclusions made from the somewhat puzzling results of the DCQE. While we focus on using an array of microwave kinetic induction detectors for this experiment, other, potentially better-suited superconducting devices are also considered.

Observations of the Delayed-Choice Quantum Eraser in a Macroscopic System

Observations of the Delayed-Choice Quantum Eraser in a Macroscopic System

Engineering of Hong-Ou-Mandel interference with effective noise

The Hong-Ou-Mandel effect lies at the heart of quantum interferometry, having multiple applications in the field of quantum information processing and no classical counterpart. Despite its popularity, only a few works have considered polarization-frequency interaction within the interferometer. In this paper, we fill this gap. Our system of interest is a general biphoton polarization state that experiences effective dephasing noise by becoming entangled with the same photons' frequency state, as the photons propagate through birefringent media. The photons then meet at a beam splitter, where either coincidence or bunching occurs, after which the polarization-frequency interaction continues on the output paths. Along with performing extensive theoretical analysis on the coincidence probability and different polarization states, we outline multiple interesting applications that range from constructing Bell states to an alternative delayed choice quantum eraser.

The Delayed-Choice Quantum Eraser Leaves No Choice

A realizable delayed-choice quantum eraser, using a modified Mach-Zehnder (MZ) interferometer and polarization entangled photons, is theoretically analyzed here. The signal photon goes through a modified MZ interferometer, and the polarization of the idler photon provides path information for the signal photon. The setup is very similar to the delayed-choice quantum eraser experimentally studied by the Vienna group. In the class of quantum erasers with discrete output states, it is easy to see that the delayed mode leaves no choice for the experimenter. The which-way information is always erased, and every detected signal photon fixes the polarization state of the idler, and thus gives information on precisely how the signal photon traversed the two paths. The analysis shows that the Vienna delayed-choice quantum eraser is the first experimental demonstration of the fact that the delayed mode leaves no choice for the experimenter, and the which-way information is always erased. Additionally it is shown that this argument holds even in a conventional two-slit quantum eraser. Every photon registered anywhere on the screen, fixes the state of the two-state which-way detector in a unique mutually unbiased basis. In the delayed-choice quantum eraser experiments, the role of mutually unbiased basis sets for the which-way detector, has been overlooked till now.

Classical model of a delayed-choice quantum eraser

Wheeler's delayed-choice experiment was conceived to illustrate the paradoxical nature of wave-particle duality in quantum mechanics. In the experiment, quantum light can exhibit either wave-like interference patterns or particle-like anti-correlations, depending upon the (possibly delayed) choice of the experimenter. A variant known as the quantum eraser uses entangled light to recover the lost interference in a seemingly nonlocal and retrocausal manner. Although it is believed that this behavior is incompatible with classical physics, here we show that the observed quantum phenomena can be reproduced by adopting a simple deterministic detector model and supposing the existence of a random zero-point electromagnetic field.

The Delayed Quantum Eraser Experiment Explained Classically

This paper discusses the well-known delayed choice Quantum Eraser experiment performed by Kim et al. in 2000 and analyzes it from a Classical Physics perspective. I have included a diagram of the setup used in the experiment. I show that the result of the experiment can be explained by Classical Physics and does not require “Spooky action at a distance” due to entangled particles, as Einstein famously once put it, nor events modifying the past due to the delayed choice aspect of the experiment.

Demystifying the delayed-choice quantum eraser

The delayed-choice quantum eraser has long been a subject of controversy, and has been looked at as being incomprehensible to having retro-causal effect in time. Here the delayed-choice quantum eraser is theoretically analyzed using standard quantum mechanics. Employing a Mach–Zehnder interferometer, instead of a conventional two-slit interference, brings in surprising clarity. Some common mistakes in interpreting the experiment are pointed out. It is demonstrated that in the delayed mode there is no which-way information present after the particle is registered on the screen or the final detectors, contrary to popular belief. However, it is shown that another kind of path information is present even after the particle is registered in the final detectors. The registered particle can be used to predict the results of certain yet to be made measurements on the which-way detector. This novel correlation can be tested in a careful experiment. It is consequently argued that there is no big mystery in the experiment, and no retro-causal effect whatsoever.

Incorporating the Stern-Gerlach delayed-choice quantum eraser into the undergraduate quantum mechanics curriculum

As “Stern-Gerlach first” becomes increasingly popular in the undergraduate quantum mechanics curriculum, we show how one can extend the treatment found in conventional textbooks to cover some exciting new quantum phenomena. Namely, we illustrate how one can describe a delayed choice variant of the quantum eraser which is realized within the Stern-Gerlach framework. Covering this material allows the instructor to reinforce notions of changes in basis functions, quantum superpositions, quantum measurements, and the complementarity principle as expressed in whether we know “which-way” information or not. It also allows the instructor to dispel common misconceptions of when a measurement occurs and when a system is in a superposition of states.

Taming the Delayed Choice Quantum Eraser

I discuss the delayed choice quantum eraser experiment by drawing an analogy to a Bell-type measurement and giving a straightforward account in standard quantum mechanics. The delayed choice quantum eraser experiment turns out to resemble a Bell-type scenario in which the resolution of the paradox is rather trivial, and so there really is no mystery. At first glance, the experiment suggests that measurements on one part of an entangled photon pair (the idler) can be employed to control whether the measurement outcome of the other part of the photon pair (the signal) produces interference fringes at a screen after being sent through a double slit. Significantly, the choice whether there is interference or not can be made long after the signal photon encounters the screen. The results of the experiment have been alleged to invoke some sort of backwards in time influence. I argue that this issue can be eliminated by taking into proper account the role of the signal photon. Likewise, in the de Broglie–Bohm picture the trajectories of the particle can be given a well-defined description at any instant of time during the experiment. Thus, it is again clear that there is no need to resort to any kind of backwards in time influence.Quanta 2019; 8: 44-56.

时空阶梯理论对双缝实验的解释——延迟选择量子擦除实验的本质

时空阶梯理论对双缝实验的解释——延迟选择量子擦除实验的本质

Nature of Time in Quantum Mechanics

We have an uncertain future continuously coming into existence relative to the instant absorption and emission of photon energy. The future is a blank canvas that we can interact with forming the possible into the actual. And the future we are dealing with is from our point of reference. The future is unfolding with each photonelectron interaction with the respective elements of the periodic table and the individual waves formed by the electromagnetic spectrum. It’s a process of energy exchange that forms reality. If we look at the quantum world, the ‘past’ is represented by anti-matter annihilation which maintains a balance between matter and anti-matter showing a balance between the future and the past. In the Delayed Choice Quantum Eraser Experiment, time is unfolding photon by photon within the experiment, within our frame of reference. But we have an infinite number of reference frames coming in and out of existence with a timeline for each object. What is our past might be the future to an observer from a different frame of reference. Everything is relative.

Consciousness is an Entity with Entangled States: Correlating the Measurement Problem with Non-Local Consciousness

The difficulty in solving the measurement problem may derive from a lack of thorough understanding of the nature of consciousness. Recent findings from parapsychological research and confirmed reports of veridical perceptions during near death experiences (NDEs) show that consciousness can acquire non-local information and may act as an independent entity outside of the body. But how apparent nonlocal properties of consciousness correlate with the measurement problem is unclear. Starting from the assumption that discrete states of consciousness are entangled with corresponding superposed eigenstates of an observed system, the findings of the double-slit experiment and delayed-choice quantum eraser experiment are reanalyzed and the non-locality of consciousness entity is derived from first principles. I propose experimental designs aimed at testing non-local entanglement between multiple consciousness entities that may help explain anomalous phenomena including telepathy, the role of “which-path information” in a measurement, and the nature of consciousness in non-human animals. Finally, I discuss the origin of the perception of time and the relationship between time and consciousness.

Astronomical random numbers for quantum foundations experiments

Photons from distant astronomical sources can be used as a classical source of randomness to improve fundamental tests of quantum nonlocality, wave-particle duality, and local realism through Bell's inequality and delayed-choice quantum eraser tests inspired by Wheeler's cosmic-scale Mach-Zehnder interferometer gedankenexperiment. Such sources of random numbers may also be useful for information-theoretic applications such as key distribution for quantum cryptography. Building on the design of an "astronomical random-number generator" developed for the recent "cosmic Bell" experiment [Handsteiner et al., Phys. Rev. Lett. 118, 060401 (2017)], in this paper we report on the design and characterization of a device that, with 20-nanosecond latency, outputs a bit based on whether the wavelength of an incoming photon is greater than or less than 700 nm. Using the one-meter telescope at the Jet Propulsion Laboratory (JPL) Table Mountain Observatory, we generated random bits from astronomical photons in both color channels from 50 stars of varying color and magnitude, and from 12 quasars with redshifts up to $z = 3.9$. With stars, we achieved bit rates of $\sim 1 \times 10^6$ Hz / m$^2$, limited by saturation for our single-photon detectors, and with quasars of magnitudes between 12.9 and 16, we achieved rates between $\sim 10^2$ and $2 \times 10^3$ Hz /m$^2$. For bright quasars, the resulting bitstreams exhibit sufficiently low amounts of statistical predictability as quantified by the mutual information. In addition, a sufficiently high fraction of bits generated are of true astronomical origin in order to address both the locality and freedom-of-choice loopholes when used to set the measurement settings in a test of the Bell-CHSH inequality.

Delayed-choice tunable quantum eraser under cavity QED Mach-Zehnder setup

We propose a Delayed-Choice Quantum Eraser (DCQE) operating under Mach-Zehnder setup augmented with the off resonant cavity QED atom-field interactions. The proposed DCQE completely highlights all the counterintuitive ideas of the quantum theory while shedding ample light over the themes of coherence, conception of the time in quantum theory, measurement, information and the entropy. The setup is certainly helpful to clarify some features of the ongoing dialogue about the ontological (epistemological) nature of the state vector. Furthermore, this proposal for the fully deterministic experiment can be easily executed under the prevailing research scenario with good fidelity.